Zoltan2_PartitioningSolution.hpp

Go to the documentation of this file.

// @HEADER
//
// ***********************************************************************
//
//   Zoltan2: A package of combinatorial algorithms for scientific computing
//                  Copyright 2012 Sandia Corporation
//
// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
// the U.S. Government retains certain rights in this software.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// 3. Neither the name of the Corporation nor the names of the
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY SANDIA CORPORATION "AS IS" AND ANY
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL SANDIA CORPORATION OR THE
// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//
// Questions? Contact Karen Devine      (kddevin@sandia.gov)
//                    Erik Boman        (egboman@sandia.gov)
//                    Siva Rajamanickam (srajama@sandia.gov)
//
// ***********************************************************************
//
// @HEADER
 
#ifndef _ZOLTAN2_PARTITIONINGSOLUTION_HPP_
#define _ZOLTAN2_PARTITIONINGSOLUTION_HPP_
 
namespace Zoltan2 {
template <typename Adapter>
class PartitioningSolution;
}
 
#include <Zoltan2_Environment.hpp>
#include <Zoltan2_Solution.hpp>
#include <Zoltan2_GreedyMWM.hpp>
#include <Zoltan2_Algorithm.hpp>
#include <Zoltan2_CoordinatePartitioningGraph.hpp>
#include <cmath>
#include <algorithm>
#include <vector>
#include <limits>
 
#ifdef _MSC_VER
#define NOMINMAX
#include <windows.h>
#endif
 
 
namespace Zoltan2 {
 
template <typename Adapter>
  class PartitioningSolution : public Solution
{
public:
 
#ifndef DOXYGEN_SHOULD_SKIP_THIS
  typedef typename Adapter::gno_t gno_t;
  typedef typename Adapter::scalar_t scalar_t;
  typedef typename Adapter::lno_t lno_t;
  typedef typename Adapter::part_t part_t;
  typedef typename Adapter::user_t user_t;
#endif
 
  PartitioningSolution( const RCP<const Environment> &env,
    const RCP<const Comm<int> > &comm,
    int nUserWeights, 
    const RCP<Algorithm<Adapter> > &algorithm = Teuchos::null);
 
  PartitioningSolution(const RCP<const Environment> &env,
    const RCP<const Comm<int> > &comm,
    int nUserWeights, ArrayView<ArrayRCP<part_t> > reqPartIds,
    ArrayView<ArrayRCP<scalar_t> > reqPartSizes,
    const RCP<Algorithm<Adapter> > &algorithm = Teuchos::null);
 
  // Information that the algorithm may wish to query.
 
  size_t getTargetGlobalNumberOfParts() const { return nGlobalParts_; }
 
  size_t getActualGlobalNumberOfParts() const { return nGlobalPartsSolution_; }
 
  size_t getLocalNumberOfParts() const { return nLocalParts_; }
 
  scalar_t getLocalFractionOfPart() const { return localFraction_; }
 
  bool oneToOnePartDistribution() const { return onePartPerProc_; }
 
  const int *getPartDistribution() const {
    if (partDist_.size() > 0) return &partDist_[0];
    else return NULL;
  }
 
  const part_t *getProcDistribution() const {
    if (procDist_.size() > 0) return &procDist_[0];
    else return NULL;
  }
 
  int getNumberOfCriteria() const { return nWeightsPerObj_; }
 
 
  bool criteriaHasUniformPartSizes(int idx) const { return pSizeUniform_[idx];}
 
  scalar_t getCriteriaPartSize(int idx, part_t part) const {
    if (pSizeUniform_[idx])
      return 1.0 / nGlobalParts_;
    else if (pCompactIndex_[idx].size())
      return pSize_[idx][pCompactIndex_[idx][part]];
    else
      return pSize_[idx][part];
  }
 
  bool criteriaHaveSamePartSizes(int c1, int c2) const;
 
  // Method used by the algorithm to set results.
 
  void setParts(ArrayRCP<part_t> &partList);
 
 
  void RemapParts();
 
  /* Return the weight of objects staying with a given remap.
   * If remap is NULL, compute weight of objects staying with given partition
   */
  long measure_stays(part_t *remap, int *idx, part_t *adj, long *wgt,
                     part_t nrhs, part_t nlhs)
  {
    long staying = 0;
    for (part_t i = 0; i < nrhs; i++) { 
      part_t k = (remap ? remap[i] : i);
      for (part_t j = idx[k]; j < idx[k+1]; j++) { 
        if (i == (adj[j]-nlhs)) {
          staying += wgt[j];
          break;
        }
      }
    }
    return staying;
  }
 
  // Results that may be queried by the user, by migration methods,
  // or by metric calculation methods.
  // We return raw pointers so users don't have to learn about our
  // pointer wrappers.
 
  inline const RCP<const Comm<int> > &getCommunicator() const { return comm_;}
 
  inline const RCP<const Environment> &getEnvironment() const { return env_;}
 
  const part_t *getPartListView() const {
    if (parts_.size() > 0) return parts_.getRawPtr();
    else                   return NULL;
  }
 
  const int *getProcListView() const {
    if (procs_.size() > 0) return procs_.getRawPtr();
    else                   return NULL;
  }
 
  virtual bool isPartitioningTreeBinary() const
  {
    if (this->algorithm_ == Teuchos::null)
      throw std::logic_error("no partitioning algorithm has been run yet");
    return this->algorithm_->isPartitioningTreeBinary();
  }
 
  void getPartitionTree(part_t & numTreeVerts,
                        std::vector<part_t> & permPartNums,
                        std::vector<part_t> & splitRangeBeg,
                        std::vector<part_t> & splitRangeEnd,
                        std::vector<part_t> & treeVertParents) const {
 
    part_t numParts = static_cast<part_t>(getTargetGlobalNumberOfParts());
 
    if (this->algorithm_ == Teuchos::null)
      throw std::logic_error("no partitioning algorithm has been run yet");
    this->algorithm_->getPartitionTree(
      numParts, // may want to change how this is passed through
      numTreeVerts,
      permPartNums,
      splitRangeBeg,
      splitRangeEnd,
      treeVertParents);
  }
 
  std::vector<Zoltan2::coordinateModelPartBox> &
  getPartBoxesView() const
  {
    return this->algorithm_->getPartBoxesView();
  }
 
  //          when a point lies on a part boundary, the lowest part
  //          number on that boundary is returned.
  //          Note that not all partitioning algorithms will support
  //          this method.
  //
  //   \param dim : the number of dimensions specified for the point in space
  //   \param point : the coordinates of the point in space; array of size dim
  //   \return the part number of a part overlapping the given point
  part_t pointAssign(int dim, scalar_t *point) const
  {
    part_t p;
    try {
      if (this->algorithm_ == Teuchos::null)
        throw std::logic_error("no partitioning algorithm has been run yet");
 
      p = this->algorithm_->pointAssign(dim, point); 
    }
    Z2_FORWARD_EXCEPTIONS
    return p;
  }
 
  //   This method allocates memory for the return argument, but does not
  //   control that memory.  The user is responsible for freeing the 
  //   memory.
  //
  //   \param dim : (in) the number of dimensions specified for the box
  //   \param lower : (in) the coordinates of the lower corner of the box; 
  //                   array of size dim
  //   \param upper : (in) the coordinates of the upper corner of the box; 
  //                   array of size dim
  //   \param nPartsFound : (out) the number of parts overlapping the box
  //   \param partsFound :  (out) array of parts overlapping the box
  void boxAssign(int dim, scalar_t *lower, scalar_t *upper,
                 size_t &nPartsFound, part_t **partsFound) const
  {
    try {
      if (this->algorithm_ == Teuchos::null)
        throw std::logic_error("no partitioning algorithm has been run yet");
 
      this->algorithm_->boxAssign(dim, lower, upper, nPartsFound, partsFound); 
    }
    Z2_FORWARD_EXCEPTIONS
  }
 
 
  void getCommunicationGraph(ArrayRCP <part_t> &comXAdj,
                             ArrayRCP <part_t> &comAdj) const
  {
    try {
      if (this->algorithm_ == Teuchos::null)
        throw std::logic_error("no partitioning algorithm has been run yet");
 
      this->algorithm_->getCommunicationGraph(this, comXAdj, comAdj);
    }
    Z2_FORWARD_EXCEPTIONS
  }
 
  void getPartsForProc(int procId, double &numParts, part_t &partMin,
    part_t &partMax) const
  {
    env_->localInputAssertion(__FILE__, __LINE__, "invalid process id",
      procId >= 0 && procId < comm_->getSize(), BASIC_ASSERTION);
 
    procToPartsMap(procId, numParts, partMin, partMax);
  }
 
  void getProcsForPart(part_t partId, part_t &procMin, part_t &procMax) const
  {
    env_->localInputAssertion(__FILE__, __LINE__, "invalid part id",
      partId >= 0 && partId < nGlobalParts_, BASIC_ASSERTION);
 
    partToProcsMap(partId, procMin, procMax);
  }
 
private:
  void partToProc(bool doCheck, bool haveNumLocalParts, bool haveNumGlobalParts,
    int numLocalParts, int numGlobalParts);
 
  void procToPartsMap(int procId, double &numParts, part_t &partMin,
    part_t &partMax) const;
 
  void partToProcsMap(part_t partId, int &procMin, int &procMax) const;
 
  void setPartDistribution();
 
  void setPartSizes(ArrayView<ArrayRCP<part_t> > reqPartIds,
    ArrayView<ArrayRCP<scalar_t> > reqPartSizes);
 
  void computePartSizes(int widx, ArrayView<part_t> ids,
    ArrayView<scalar_t> sizes);
 
  void broadcastPartSizes(int widx);
 
 
  RCP<const Environment> env_;             // has application communicator
  const RCP<const Comm<int> > comm_;       // the problem communicator
 
  //part box boundaries as a result of geometric partitioning algorithm.
  RCP<std::vector<Zoltan2::coordinateModelPartBox> > partBoxes;
 
  part_t nGlobalParts_;// target global number of parts
  part_t nLocalParts_; // number of parts to be on this process
 
  scalar_t localFraction_; // approx fraction of a part on this process
  int nWeightsPerObj_;      // if user has no weights, this is 1  TODO:  WHY???
 
  // If process p is to be assigned part p for all p, then onePartPerProc_
  // is true. Otherwise it is false, and either procDist_ or partDist_
  // describes the allocation of parts to processes.
  //
  // If parts are never split across processes, then procDist_ is defined
  // as follows:
  //
  //   partId              = procDist_[procId]
  //   partIdNext          = procDist_[procId+1]
  //   globalNumberOfParts = procDist_[numProcs]
  //
  // meaning that the parts assigned to process procId range from
  // [partId, partIdNext).  If partIdNext is the same as partId, then
  // process procId has no parts.
  //
  // If the number parts is less than the number of processes, and the
  // user did not specify "num_local_parts" for each of the processes, then
  // parts are split across processes, and partDist_ is defined rather than
  // procDist_.
  //
  //   procId              = partDist_[partId]
  //   procIdNext          = partDist_[partId+1]
  //   globalNumberOfProcs = partDist_[numParts]
  //
  // which implies that the part partId is shared by processes in the
  // the range [procId, procIdNext).
  //
  // We use std::vector so we can use upper_bound algorithm
 
  bool             onePartPerProc_;   // either this is true...
  std::vector<int>      partDist_;      // or this is defined ...
  std::vector<part_t> procDist_;      // or this is defined.
  bool procDistEquallySpread_;        // if procDist_ is used and
                                      // #parts > #procs and
                                      // num_local_parts is not specified,
                                      // parts are evenly distributed to procs
 
  // In order to minimize the storage required for part sizes, we
  // have three different representations.
  //
  // If the part sizes for weight index w are all the same, then:
  //    pSizeUniform_[w] = true
  //    pCompactIndex_[w].size() = 0
  //    pSize_[w].size() = 0
  //
  // and the size for part p is 1.0 / nparts.
  //
  // If part sizes differ for each part in weight index w, but there
  // are no more than 64 distinct sizes:
  //    pSizeUniform_[w] = false
  //    pCompactIndex_[w].size() = number of parts
  //    pSize_[w].size() = number of different sizes
  //
  // and the size for part p is pSize_[pCompactIndex_[p]].
  //
  // If part sizes differ for each part in weight index w, and there
  // are more than 64 distinct sizes:
  //    pSizeUniform_[w] = false
  //    pCompactIndex_[w].size() = 0
  //    pSize_[w].size() = nparts
  //
  // and the size for part p is pSize_[p].
  //
  // NOTE: If we expect to have similar cases, i.e. a long list of scalars
  //   where it is highly possible that just a few unique values appear,
  //   then we may want to make this a class.  The advantage is that we
  //   save a long list of 1-byte indices instead of a long list of scalars.
 
  ArrayRCP<bool> pSizeUniform_;
  ArrayRCP<ArrayRCP<unsigned char> > pCompactIndex_;
  ArrayRCP<ArrayRCP<scalar_t> > pSize_;
 
  // The algorithm sets these values upon completion.
 
  ArrayRCP<part_t> parts_;      // part number assigned to localid[i]
 
  bool haveSolution_;
 
  part_t nGlobalPartsSolution_; // global number of parts in solution
 
  // The solution calculates this from the part assignments,
  // unless onePartPerProc_.
 
  ArrayRCP<int> procs_;       // process rank assigned to localid[i]
 
  // Algorithm used to compute the solution; 
  // needed for post-processing with pointAssign or getCommunicationGraph
  const RCP<Algorithm<Adapter> > algorithm_;  // 
};
 
// Definitions
 
template <typename Adapter>
  PartitioningSolution<Adapter>::PartitioningSolution(
    const RCP<const Environment> &env,
    const RCP<const Comm<int> > &comm,
    int nUserWeights,
    const RCP<Algorithm<Adapter> > &algorithm)
    : env_(env), comm_(comm),
      partBoxes(),
      nGlobalParts_(0), nLocalParts_(0),
      localFraction_(0),  nWeightsPerObj_(),
      onePartPerProc_(false), partDist_(), procDist_(),
      procDistEquallySpread_(false),
      pSizeUniform_(), pCompactIndex_(), pSize_(),
      parts_(), haveSolution_(false), nGlobalPartsSolution_(0),
      procs_(), algorithm_(algorithm)
{
  nWeightsPerObj_ = (nUserWeights ? nUserWeights : 1);  // TODO:  WHY??  WHY NOT ZERO?
 
  setPartDistribution();
 
  // We must call setPartSizes() because part sizes may have
  // been provided by the user on other processes.
 
  ArrayRCP<part_t> *noIds = new ArrayRCP<part_t> [nWeightsPerObj_];
  ArrayRCP<scalar_t> *noSizes = new ArrayRCP<scalar_t> [nWeightsPerObj_];
  ArrayRCP<ArrayRCP<part_t> > ids(noIds, 0, nWeightsPerObj_, true);
  ArrayRCP<ArrayRCP<scalar_t> > sizes(noSizes, 0, nWeightsPerObj_, true);
 
  setPartSizes(ids.view(0, nWeightsPerObj_), sizes.view(0, nWeightsPerObj_));
 
  env_->memory("After construction of solution");
}
 
template <typename Adapter>
  PartitioningSolution<Adapter>::PartitioningSolution(
    const RCP<const Environment> &env,
    const RCP<const Comm<int> > &comm,
    int nUserWeights,
    ArrayView<ArrayRCP<part_t> > reqPartIds,
    ArrayView<ArrayRCP<scalar_t> > reqPartSizes,
    const RCP<Algorithm<Adapter> > &algorithm)
    : env_(env), comm_(comm),
      partBoxes(),
      nGlobalParts_(0), nLocalParts_(0),
      localFraction_(0),  nWeightsPerObj_(),
      onePartPerProc_(false), partDist_(), procDist_(),
      procDistEquallySpread_(false),
      pSizeUniform_(), pCompactIndex_(), pSize_(),
      parts_(), haveSolution_(false), nGlobalPartsSolution_(0),
      procs_(), algorithm_(algorithm)
{
  nWeightsPerObj_ = (nUserWeights ? nUserWeights : 1);  // TODO:  WHY?? WHY NOT ZERO?
 
  setPartDistribution();
 
  setPartSizes(reqPartIds, reqPartSizes);
 
  env_->memory("After construction of solution");
}
 
template <typename Adapter>
  void PartitioningSolution<Adapter>::setPartDistribution()
{
  // Did the caller define num_global_parts and/or num_local_parts?
 
  const ParameterList &pl = env_->getParameters();
  size_t haveGlobalNumParts=0, haveLocalNumParts=0;
  int numLocal=0, numGlobal=0;
 
  const Teuchos::ParameterEntry *pe = pl.getEntryPtr("num_global_parts");
 
  if (pe){
    haveGlobalNumParts = 1;
    nGlobalParts_ = part_t(pe->getValue(&nGlobalParts_));
    numGlobal = nGlobalParts_;
  }
 
  pe = pl.getEntryPtr("num_local_parts");
 
  if (pe){
    haveLocalNumParts = 1;
    nLocalParts_ = part_t(pe->getValue(&nLocalParts_));
    numLocal = nLocalParts_;
  }
 
  try{
    // Sets onePartPerProc_, partDist_, and procDist_
 
    partToProc(true, haveLocalNumParts, haveGlobalNumParts,
      numLocal, numGlobal);
  }
  Z2_FORWARD_EXCEPTIONS
 
  int nprocs = comm_->getSize();
  int rank = comm_->getRank();
 
  if (onePartPerProc_){
    nGlobalParts_ = nprocs;
    nLocalParts_ = 1;
  }
  else if (partDist_.size() > 0){   // more procs than parts
    nGlobalParts_ = partDist_.size() - 1;
    int pstart = partDist_[0];
    for (part_t i=1; i <= nGlobalParts_; i++){
      int pend = partDist_[i];
      if (rank >= pstart && rank < pend){
        int numOwners = pend - pstart;
        nLocalParts_ = 1;
        localFraction_ = 1.0 / numOwners;
        break;
      }
      pstart = pend;
    }
  }
  else if (procDist_.size() > 0){  // more parts than procs
    nGlobalParts_ = procDist_[nprocs];
    nLocalParts_ = procDist_[rank+1] - procDist_[rank];
  }
  else {
    throw std::logic_error("partToProc error");
  }
 
}
 
template <typename Adapter>
  void PartitioningSolution<Adapter>::setPartSizes(
    ArrayView<ArrayRCP<part_t> > ids, ArrayView<ArrayRCP<scalar_t> > sizes)
{
  int widx = nWeightsPerObj_;
  bool fail=false;
 
  size_t *countBuf = new size_t [widx*2];
  ArrayRCP<size_t> counts(countBuf, 0, widx*2, true);
 
  fail = ((ids.size() != widx) || (sizes.size() != widx));
 
  for (int w=0; !fail && w < widx; w++){
    counts[w] = ids[w].size();
    if (ids[w].size() != sizes[w].size()) fail=true;
  }
 
  env_->globalBugAssertion(__FILE__, __LINE__, "bad argument arrays", fail==0,
    COMPLEX_ASSERTION, comm_);
 
  // Are all part sizes the same?  This is the common case.
 
  ArrayRCP<scalar_t> *emptySizes= new ArrayRCP<scalar_t> [widx];
  pSize_ = arcp(emptySizes, 0, widx);
 
  ArrayRCP<unsigned char> *emptyIndices= new ArrayRCP<unsigned char> [widx];
  pCompactIndex_ = arcp(emptyIndices, 0, widx);
 
  bool *info = new bool [widx];
  pSizeUniform_ = arcp(info, 0, widx);
  for (int w=0; w < widx; w++)
    pSizeUniform_[w] = true;
 
  if (nGlobalParts_ == 1){
    return;   // there's only one part in the whole problem
  }
 
  size_t *ptr1 = counts.getRawPtr();
  size_t *ptr2 = counts.getRawPtr() + widx;
 
  try{
    reduceAll<int, size_t>(*comm_, Teuchos::REDUCE_MAX, widx, ptr1, ptr2);
  }
  Z2_THROW_OUTSIDE_ERROR(*env_);
 
  bool zero = true;
 
  for (int w=0; w < widx; w++)
    if (counts[widx+w] > 0){
      zero = false;
      pSizeUniform_[w] = false;
    }
 
  if (zero) // Part sizes for all criteria are uniform.
    return;
 
  // Compute the part sizes for criteria for which part sizes were
  // supplied.  Normalize for each criteria so part sizes sum to one.
 
  int nprocs = comm_->getSize();
  int rank = comm_->getRank();
 
  for (int w=0; w < widx; w++){
    if (pSizeUniform_[w]) continue;
 
    // Send all ids and sizes to one process.
    // (There is no simple gather method in Teuchos.)
 
    part_t length = ids[w].size();
    part_t *allLength = new part_t [nprocs];
    Teuchos::gatherAll<int, part_t>(*comm_, 1, &length,
      nprocs, allLength);
 
    if (rank == 0){
      int total = 0;
      for (int i=0; i < nprocs; i++)
        total += allLength[i];
 
      part_t *partNums = new part_t [total];
      scalar_t *partSizes = new scalar_t [total];
 
      ArrayView<part_t> idArray(partNums, total);
      ArrayView<scalar_t> sizeArray(partSizes, total);
 
      if (length > 0){
        for (int i=0; i < length; i++){
          *partNums++ = ids[w][i];
          *partSizes++ = sizes[w][i];
        }
      }
 
      for (int p=1; p < nprocs; p++){
        if (allLength[p] > 0){
          Teuchos::receive<int, part_t>(*comm_, p,
            allLength[p], partNums);
          Teuchos::receive<int, scalar_t>(*comm_, p,
            allLength[p], partSizes);
          partNums += allLength[p];
          partSizes += allLength[p];
        }
      }
 
      delete [] allLength;
 
      try{
        computePartSizes(w, idArray, sizeArray);
      }
      Z2_FORWARD_EXCEPTIONS
 
      delete [] idArray.getRawPtr();
      delete [] sizeArray.getRawPtr();
    }
    else{
      delete [] allLength;
      if (length > 0){
        Teuchos::send<int, part_t>(*comm_, length, ids[w].getRawPtr(), 0);
        Teuchos::send<int, scalar_t>(*comm_, length, sizes[w].getRawPtr(), 0);
      }
    }
 
    broadcastPartSizes(w);
  }
}
 
template <typename Adapter>
  void PartitioningSolution<Adapter>::broadcastPartSizes(int widx)
{
  env_->localBugAssertion(__FILE__, __LINE__, "preallocations",
    pSize_.size()>widx &&
    pSizeUniform_.size()>widx && pCompactIndex_.size()>widx,
    COMPLEX_ASSERTION);
 
  int rank = comm_->getRank();
  int nprocs = comm_->getSize();
  part_t nparts = nGlobalParts_;
 
  if (nprocs < 2)
    return;
 
  char flag=0;
 
  if (rank == 0){
    if (pSizeUniform_[widx] == true)
      flag = 1;
    else if (pCompactIndex_[widx].size() > 0)
      flag = 2;
    else
      flag = 3;
  }
 
  try{
    Teuchos::broadcast<int, char>(*comm_, 0, 1, &flag);
  }
  Z2_THROW_OUTSIDE_ERROR(*env_);
 
  if (flag == 1){
    if (rank > 0)
      pSizeUniform_[widx] = true;
 
    return;
  }
 
  if (flag == 2){
 
    // broadcast the indices into the size list
 
    unsigned char *idxbuf = NULL;
 
    if (rank > 0){
      idxbuf = new unsigned char [nparts];
      env_->localMemoryAssertion(__FILE__, __LINE__, nparts, idxbuf);
    }
    else{
      env_->localBugAssertion(__FILE__, __LINE__, "index list size",
        pCompactIndex_[widx].size() == nparts, COMPLEX_ASSERTION);
      idxbuf = pCompactIndex_[widx].getRawPtr();
    }
 
    try{
      // broadcast of unsigned char is not supported
      Teuchos::broadcast<int, char>(*comm_, 0, nparts,
        reinterpret_cast<char *>(idxbuf));
    }
    Z2_THROW_OUTSIDE_ERROR(*env_);
 
    if (rank > 0)
      pCompactIndex_[widx] = arcp(idxbuf, 0, nparts, true);
 
    // broadcast the list of different part sizes
 
    unsigned char maxIdx=0;
    for (part_t p=0; p < nparts; p++)
      if (idxbuf[p] > maxIdx) maxIdx = idxbuf[p];
 
    int numSizes = maxIdx + 1;
 
    scalar_t *sizeList = NULL;
 
    if (rank > 0){
      sizeList = new scalar_t [numSizes];
      env_->localMemoryAssertion(__FILE__, __LINE__, numSizes, sizeList);
    }
    else{
      env_->localBugAssertion(__FILE__, __LINE__, "wrong number of sizes",
        numSizes == pSize_[widx].size(), COMPLEX_ASSERTION);
 
      sizeList = pSize_[widx].getRawPtr();
    }
 
    try{
      Teuchos::broadcast<int, scalar_t>(*comm_, 0, numSizes, sizeList);
    }
    Z2_THROW_OUTSIDE_ERROR(*env_);
 
    if (rank > 0)
      pSize_[widx] = arcp(sizeList, 0, numSizes, true);
 
    return;
  }
 
  if (flag == 3){
 
    // broadcast the size of each part
 
    scalar_t *sizeList = NULL;
 
    if (rank > 0){
      sizeList = new scalar_t [nparts];
      env_->localMemoryAssertion(__FILE__, __LINE__, nparts, sizeList);
    }
    else{
      env_->localBugAssertion(__FILE__, __LINE__, "wrong number of sizes",
        nparts == pSize_[widx].size(), COMPLEX_ASSERTION);
 
      sizeList = pSize_[widx].getRawPtr();
    }
 
    try{
      Teuchos::broadcast<int, scalar_t >(*comm_, 0, nparts, sizeList);
    }
    Z2_THROW_OUTSIDE_ERROR(*env_);
 
    if (rank > 0)
      pSize_[widx] = arcp(sizeList, 0, nparts);
 
    return;
  }
}
 
template <typename Adapter>
  void PartitioningSolution<Adapter>::computePartSizes(int widx,
    ArrayView<part_t> ids, ArrayView<scalar_t> sizes)
{
  int len = ids.size();
 
  if (len == 0){
    pSizeUniform_[widx] = true;
    return;
  }
 
  env_->localBugAssertion(__FILE__, __LINE__, "bad array sizes",
    len>0 && sizes.size()==len, COMPLEX_ASSERTION);
 
  env_->localBugAssertion(__FILE__, __LINE__, "bad index",
    widx>=0 && widx<nWeightsPerObj_, COMPLEX_ASSERTION);
 
  env_->localBugAssertion(__FILE__, __LINE__, "preallocations",
    pSize_.size()>widx &&
    pSizeUniform_.size()>widx && pCompactIndex_.size()>widx,
    COMPLEX_ASSERTION);
 
  // Check ids and sizes and find min, max and average sizes.
  // If sizes are very close to uniform, call them uniform parts.
 
  part_t nparts = nGlobalParts_;
  unsigned char *buf = new unsigned char [nparts];
  env_->localMemoryAssertion(__FILE__, __LINE__, nparts, buf);
  memset(buf, 0, nparts);
  ArrayRCP<unsigned char> partIdx(buf, 0, nparts, true);
 
  scalar_t epsilon = 10e-5 / nparts;
  scalar_t min=sizes[0], max=sizes[0], sum=0;
 
  for (int i=0; i < len; i++){
    part_t id = ids[i];
    scalar_t size = sizes[i];
 
    env_->localInputAssertion(__FILE__, __LINE__, "invalid part id",
      id>=0 && id<nparts, BASIC_ASSERTION);
 
    env_->localInputAssertion(__FILE__, __LINE__, "invalid part size", size>=0,
      BASIC_ASSERTION);
 
    // TODO: we could allow users to specify multiple sizes for the same
    // part if we add a parameter that says what we are to do with them:
    // add them or take the max.
 
    env_->localInputAssertion(__FILE__, __LINE__,
      "multiple sizes provided for one part", partIdx[id]==0, BASIC_ASSERTION);
 
    partIdx[id] = 1;    // mark that we have a size for this part
 
    if (size < min) min = size;
    if (size > max) max = size;
    sum += size;
  }
 
  if (sum == 0){
 
    // User has given us a list of parts of size 0, we'll set
    // the rest to them to equally sized parts.
 
    scalar_t *allSizes = new scalar_t [2];
    env_->localMemoryAssertion(__FILE__, __LINE__, 2, allSizes);
 
    ArrayRCP<scalar_t> sizeArray(allSizes, 0, 2, true);
 
    int numNonZero = nparts - len;
 
    allSizes[0] = 0.0;
    allSizes[1] = 1.0 / numNonZero;
 
    for (part_t p=0; p < nparts; p++)
      buf[p] = 1;                 // index to default part size
 
    for (int i=0; i < len; i++)
      buf[ids[i]] = 0;            // index to part size zero
 
    pSize_[widx] = sizeArray;
    pCompactIndex_[widx] = partIdx;
 
    return;
  }
 
  if (max - min <= epsilon){
    pSizeUniform_[widx] = true;
    return;
  }
 
  // A size for parts that were not specified:
  scalar_t avg = sum / nparts;
 
  // We are going to merge part sizes that are very close.  This takes
  // computation time now, but can save considerably in the storage of
  // all part sizes on each process.  For example, a common case may
  // be some parts are size 1 and all the rest are size 2.
 
  scalar_t *tmp = new scalar_t [len];
  env_->localMemoryAssertion(__FILE__, __LINE__, len, tmp);
  memcpy(tmp, sizes.getRawPtr(), sizeof(scalar_t) * len);
  ArrayRCP<scalar_t> partSizes(tmp, 0, len, true);
 
  std::sort(partSizes.begin(), partSizes.end());
 
  // create a list of sizes that are unique within epsilon
 
  Array<scalar_t> nextUniqueSize;
  nextUniqueSize.push_back(partSizes[len-1]);   // largest
  scalar_t curr = partSizes[len-1];
  int avgIndex = len;
  bool haveAvg = false;
  if (curr - avg <= epsilon)
     avgIndex = 0;
 
  for (int i=len-2; i >= 0; i--){
    scalar_t val = partSizes[i];
    if (curr - val > epsilon){
      nextUniqueSize.push_back(val);  // the highest in the group
      curr = val;
      if (avgIndex==len && val > avg && val - avg <= epsilon){
        // the average would be in this group
        avgIndex = nextUniqueSize.size() - 1;
        haveAvg = true;
      }
    }
  }
 
  partSizes.clear();
 
  size_t numSizes = nextUniqueSize.size();
  int sizeArrayLen = numSizes;
 
  if (numSizes < 64){
    // We can store the size for every part in a compact way.
 
    // Create a list of all sizes in increasing order
 
    if (!haveAvg) sizeArrayLen++;   // need to include average
 
    scalar_t *allSizes = new scalar_t [sizeArrayLen];
    env_->localMemoryAssertion(__FILE__, __LINE__, sizeArrayLen, allSizes);
    ArrayRCP<scalar_t> sizeArray(allSizes, 0, sizeArrayLen, true);
 
    int newAvgIndex = sizeArrayLen;
 
    for (int i=numSizes-1, idx=0; i >= 0; i--){
 
      if (newAvgIndex == sizeArrayLen){
 
        if (haveAvg && i==avgIndex)
          newAvgIndex = idx;
 
        else if (!haveAvg && avg < nextUniqueSize[i]){
          newAvgIndex = idx;
          allSizes[idx++] = avg;
        }
      }
 
      allSizes[idx++] = nextUniqueSize[i];
    }
 
    env_->localBugAssertion(__FILE__, __LINE__, "finding average in list",
      newAvgIndex < sizeArrayLen, COMPLEX_ASSERTION);
 
    for (int i=0; i < nparts; i++){
      buf[i] = newAvgIndex;   // index to default part size
    }
 
    sum = (nparts - len) * allSizes[newAvgIndex];
 
    for (int i=0; i < len; i++){
      int id = ids[i];
      scalar_t size = sizes[i];
      int index;
 
      // Find the first size greater than or equal to this size.
 
      if (size < avg && avg - size <= epsilon)
        index = newAvgIndex;
      else{
        typename ArrayRCP<scalar_t>::iterator found =
          std::lower_bound(sizeArray.begin(), sizeArray.end(), size);
 
        env_->localBugAssertion(__FILE__, __LINE__, "size array",
          found != sizeArray.end(), COMPLEX_ASSERTION);
 
        index = found - sizeArray.begin();
      }
 
      buf[id] = index;
      sum += allSizes[index];
    }
 
    for (int i=0; i < sizeArrayLen; i++){
      sizeArray[i] /= sum;
    }
 
    pCompactIndex_[widx] = partIdx;
    pSize_[widx] = sizeArray;
  }
  else{
    // To have access to part sizes, we must store nparts scalar_ts on
    // every process.  We expect this is a rare case.
 
    tmp = new scalar_t [nparts];
    env_->localMemoryAssertion(__FILE__, __LINE__, nparts, tmp);
 
    sum += ((nparts - len) * avg);
 
    for (int i=0; i < nparts; i++){
      tmp[i] = avg/sum;
    }
 
    for (int i=0; i < len; i++){
      tmp[ids[i]] = sizes[i]/sum;
    }
 
    pSize_[widx] = arcp(tmp, 0, nparts);
  }
}
 
template <typename Adapter>
  void PartitioningSolution<Adapter>::setParts(ArrayRCP<part_t> &partList)
{
  env_->debug(DETAILED_STATUS, "Entering setParts");
 
  size_t len = partList.size();
 
  // Find the actual number of parts in the solution, which can
  // be more or less than the nGlobalParts_ target.
  // (We may want to compute the imbalance of a given solution with
  // respect to a desired solution.  This solution may have more or
  // fewer parts that the desired solution.)
 
  part_t lMax = -1;
  part_t lMin = (len > 0 ? std::numeric_limits<part_t>::max() : 0);
  part_t gMax, gMin;
 
  for (size_t i = 0; i < len; i++) {
    if (partList[i] < lMin) lMin = partList[i];
    if (partList[i] > lMax) lMax = partList[i];
  }
  Teuchos::reduceAll<int, part_t>(*comm_, Teuchos::REDUCE_MIN, 1, &lMin, &gMin);
  Teuchos::reduceAll<int, part_t>(*comm_, Teuchos::REDUCE_MAX, 1, &lMax, &gMax);
 
  nGlobalPartsSolution_ = gMax - gMin + 1;
  parts_ = partList;
 
  // Now determine which process gets each object, if not one-to-one.
 
  if (!onePartPerProc_){
 
    int *procs = new int [len];
    env_->localMemoryAssertion(__FILE__, __LINE__, len, procs);
    procs_ = arcp<int>(procs, 0, len);
 
    if (len > 0) {
      part_t *parts = partList.getRawPtr();
  
      if (procDist_.size() > 0){    // parts are not split across procs
  
        int procId;
        for (size_t i=0; i < len; i++){
          partToProcsMap(parts[i], procs[i], procId);
        }
      }
      else{  // harder - we need to split the parts across multiple procs
  
        lno_t *partCounter = new lno_t [nGlobalPartsSolution_];
        env_->localMemoryAssertion(__FILE__, __LINE__, nGlobalPartsSolution_,
          partCounter);
  
        int numProcs = comm_->getSize();
  
        //MD NOTE: there was no initialization for partCounter.
        //I added the line below, correct me if I am wrong.
        memset(partCounter, 0, sizeof(lno_t) * nGlobalPartsSolution_);
  
        for (typename ArrayRCP<part_t>::size_type i=0; i < partList.size(); i++)
          partCounter[parts[i]]++;
  
        lno_t *procCounter = new lno_t [numProcs];
        env_->localMemoryAssertion(__FILE__, __LINE__, numProcs, procCounter);
  
        int proc1;
        int proc2 = partDist_[0];
  
        for (part_t part=1; part < nGlobalParts_; part++){
          proc1 = proc2;
          proc2 = partDist_[part+1];
          int numprocs = proc2 - proc1;
  
          double dNum = partCounter[part];
          double dProcs = numprocs;
  
          //std::cout << "dNum:" << dNum << " dProcs:" << dProcs << std::endl;
          double each = floor(dNum/dProcs);
          double extra = fmod(dNum,dProcs);
  
          for (int proc=proc1, i=0; proc<proc2; proc++, i++){
            if (i < extra)
              procCounter[proc] = lno_t(each) + 1;
            else
              procCounter[proc] = lno_t(each);
          }
        }
  
        delete [] partCounter;
  
        for (typename ArrayRCP<part_t>::size_type i=0; i < partList.size(); i++){
          if (partList[i] >= nGlobalParts_){
            // Solution has more parts that targeted.  These
            // objects just remain on this process.
            procs[i] = comm_->getRank();
            continue;
          }
          part_t partNum = parts[i];
          proc1 = partDist_[partNum];
          proc2 = partDist_[partNum + 1];
  
          int proc;
          for (proc=proc1; proc < proc2; proc++){
            if (procCounter[proc] > 0){
              procs[i] = proc;
              procCounter[proc]--;
              break;
            }
          }
          env_->localBugAssertion(__FILE__, __LINE__, "part to proc",
            proc < proc2, COMPLEX_ASSERTION);
        }
  
        delete [] procCounter;
      }
    }
  }
 
  // Now that parts_ info is back on home process, remap the parts.
  // TODO:  The parts will be inconsistent with the proc assignments after
  // TODO:  remapping.  This problem will go away after we separate process
  // TODO:  mapping from setParts.  But for MueLu's use case, the part
  // TODO:  remapping is all that matters; they do not use the process mapping.
  bool doRemap = false;
  const Teuchos::ParameterEntry *pe =
                 env_->getParameters().getEntryPtr("remap_parts");
  if (pe) doRemap = pe->getValue(&doRemap);
  if (doRemap) RemapParts();
 
  haveSolution_ = true;
 
  env_->memory("After Solution has processed algorithm's answer");
  env_->debug(DETAILED_STATUS, "Exiting setParts");
}
 
 
template <typename Adapter>
  void PartitioningSolution<Adapter>::procToPartsMap(int procId,
    double &numParts, part_t &partMin, part_t &partMax) const
{
  if (onePartPerProc_){
    numParts = 1.0;
    partMin = partMax = procId;
  }
  else if (procDist_.size() > 0){
    partMin = procDist_[procId];
    partMax = procDist_[procId+1] - 1;
    numParts = procDist_[procId+1] - partMin;
  }
  else{
    // find the first p such that partDist_[p] > procId
 
    std::vector<int>::const_iterator entry;
    entry = std::upper_bound(partDist_.begin(), partDist_.end(), procId);
 
    size_t partIdx = entry - partDist_.begin();
    int numProcs = partDist_[partIdx] - partDist_[partIdx-1];
    partMin = partMax = int(partIdx) - 1;
    numParts = 1.0 / numProcs;
  }
}
 
template <typename Adapter>
  void PartitioningSolution<Adapter>::partToProcsMap(part_t partId,
    int &procMin, int &procMax) const
{
  if (partId >= nGlobalParts_){
    // setParts() may be given an initial solution which uses a
    // different number of parts than the desired solution.  It is
    // still a solution.  We keep it on this process.
    procMin = procMax = comm_->getRank();
  }
  else if (onePartPerProc_){
    procMin = procMax = int(partId);
  }
  else if (procDist_.size() > 0){
    if (procDistEquallySpread_) {
      // Avoid binary search.
      double fProcs = comm_->getSize();
      double fParts = nGlobalParts_;
      double each = fParts / fProcs;
      procMin = int(partId / each);
      while (procDist_[procMin] > partId) procMin--;
      while (procDist_[procMin+1] <= partId) procMin++;
      procMax = procMin;
    }
    else {
      // find the first p such that procDist_[p] > partId.
      // For now, do a binary search.
 
      typename std::vector<part_t>::const_iterator entry;
      entry = std::upper_bound(procDist_.begin(), procDist_.end(), partId);
 
      size_t procIdx = entry - procDist_.begin();
      procMin = procMax = int(procIdx) - 1;
    }
  }
  else{
    procMin = partDist_[partId];
    procMax = partDist_[partId+1] - 1;
  }
}
 
template <typename Adapter>
  bool PartitioningSolution<Adapter>::criteriaHaveSamePartSizes(
    int c1, int c2) const
{
  if (c1 < 0 || c1 >= nWeightsPerObj_ || c2 < 0 || c2 >= nWeightsPerObj_ )
    throw std::logic_error("criteriaHaveSamePartSizes error");
 
  bool theSame = false;
 
  if (c1 == c2)
    theSame = true;
 
  else if (pSizeUniform_[c1] == true && pSizeUniform_[c2] == true)
    theSame = true;
 
  else if (pCompactIndex_[c1].size() == pCompactIndex_[c2].size()){
    theSame = true;
    bool useIndex = pCompactIndex_[c1].size() > 0;
    if (useIndex){
      for (part_t p=0; theSame && p < nGlobalParts_; p++)
        if (pSize_[c1][pCompactIndex_[c1][p]] !=
            pSize_[c2][pCompactIndex_[c2][p]])
          theSame = false;
    }
    else{
      for (part_t p=0; theSame && p < nGlobalParts_; p++)
        if (pSize_[c1][p] != pSize_[c2][p])
          theSame = false;
    }
  }
 
  return theSame;
}
 
template <typename Adapter>
  void PartitioningSolution<Adapter>::partToProc(
    bool doCheck, bool haveNumLocalParts, bool haveNumGlobalParts,
    int numLocalParts, int numGlobalParts)
{
#ifdef _MSC_VER
  typedef SSIZE_T ssize_t;
#endif
  int nprocs = comm_->getSize();
  ssize_t reducevals[4];
  ssize_t sumHaveGlobal=0, sumHaveLocal=0;
  ssize_t sumGlobal=0, sumLocal=0;
  ssize_t maxGlobal=0, maxLocal=0;
  ssize_t vals[4] = {haveNumGlobalParts, haveNumLocalParts,
                     numGlobalParts, numLocalParts};
 
  partDist_.clear();
  procDist_.clear();
 
  if (doCheck){
 
    try{
      reduceAll<int, ssize_t>(*comm_, Teuchos::REDUCE_SUM, 4, vals, reducevals);
    }
    Z2_THROW_OUTSIDE_ERROR(*env_);
 
    sumHaveGlobal = reducevals[0];
    sumHaveLocal = reducevals[1];
    sumGlobal = reducevals[2];
    sumLocal = reducevals[3];
 
    env_->localInputAssertion(__FILE__, __LINE__,
      "Either all procs specify num_global/local_parts or none do",
      (sumHaveGlobal == 0 || sumHaveGlobal == nprocs) &&
      (sumHaveLocal == 0 || sumHaveLocal == nprocs),
      BASIC_ASSERTION);
  }
  else{
    if (haveNumLocalParts)
      sumLocal = numLocalParts * nprocs;
    if (haveNumGlobalParts)
      sumGlobal = numGlobalParts * nprocs;
 
    sumHaveGlobal = haveNumGlobalParts ? nprocs : 0;
    sumHaveLocal = haveNumLocalParts ? nprocs : 0;
 
    maxLocal = numLocalParts;
    maxGlobal = numGlobalParts;
  }
 
  if (!haveNumLocalParts && !haveNumGlobalParts){
    onePartPerProc_ = true;   // default if user did not specify
    return;
  }
 
  if (haveNumGlobalParts){
    if (doCheck){
      vals[0] = numGlobalParts;
      vals[1] = numLocalParts;
      try{
        reduceAll<int, ssize_t>(
          *comm_, Teuchos::REDUCE_MAX, 2, vals, reducevals);
      }
      Z2_THROW_OUTSIDE_ERROR(*env_);
 
      maxGlobal = reducevals[0];
      maxLocal = reducevals[1];
 
      env_->localInputAssertion(__FILE__, __LINE__,
        "Value for num_global_parts is different on different processes.",
        maxGlobal * nprocs == sumGlobal, BASIC_ASSERTION);
    }
 
    if (sumLocal){
      env_->localInputAssertion(__FILE__, __LINE__,
        "Sum of num_local_parts does not equal requested num_global_parts",
        sumLocal == numGlobalParts, BASIC_ASSERTION);
 
      if (sumLocal == nprocs && maxLocal == 1){
        onePartPerProc_ = true;   // user specified one part per proc
        return;
      }
    }
    else{
      if (maxGlobal == nprocs){
        onePartPerProc_ = true;   // user specified num parts is num procs
        return;
      }
    }
  }
 
  // If we are here, we do not have #parts == #procs.
 
  if (sumHaveLocal == nprocs){
    //
    // We will go by the number of local parts specified.
    //
 
    try{
      procDist_.resize(nprocs+1);
    }
    catch (std::exception &e){
      throw(std::bad_alloc());
    }
 
    part_t *procArray = &procDist_[0];
 
    try{
      part_t tmp = part_t(numLocalParts);
      gatherAll<int, part_t>(*comm_, 1, &tmp, nprocs, procArray + 1);
    }
    Z2_THROW_OUTSIDE_ERROR(*env_);
 
    procArray[0] = 0;
 
    for (int proc=0; proc < nprocs; proc++)
      procArray[proc+1] += procArray[proc];
  }
  else{
    //
    // We will allocate global number of parts to the processes.
    //
    double fParts = numGlobalParts;
    double fProcs = nprocs;
 
    if (fParts < fProcs){
 
      try{
        partDist_.resize(size_t(fParts+1));
      }
      catch (std::exception &e){
        throw(std::bad_alloc());
      }
 
      int *partArray = &partDist_[0];
 
      double each = floor(fProcs / fParts);
      double extra = fmod(fProcs, fParts);
      partDist_[0] = 0;
 
      for (part_t part=0; part < numGlobalParts; part++){
        int numOwners = int(each + ((part<extra) ? 1 : 0));
        partArray[part+1] = partArray[part] + numOwners;
      }
 
      env_->globalBugAssertion(__FILE__, __LINE__, "#parts != #procs",
        partDist_[numGlobalParts] == nprocs, COMPLEX_ASSERTION, comm_);
    }
    else if (fParts > fProcs){
 
      // User did not specify local number of parts per proc;
      // Distribute the parts evenly among the procs.
 
      procDistEquallySpread_ = true;
 
      try{
        procDist_.resize(size_t(fProcs+1));
      }
      catch (std::exception &e){
        throw(std::bad_alloc());
      }
 
      part_t *procArray = &procDist_[0];
 
      double each = floor(fParts / fProcs);
      double extra = fmod(fParts, fProcs);
      procArray[0] = 0;
 
      for (int proc=0; proc < nprocs; proc++){
        part_t numParts = part_t(each + ((proc<extra) ? 1 : 0));
        procArray[proc+1] = procArray[proc] + numParts;
      }
 
      env_->globalBugAssertion(__FILE__, __LINE__, "#parts != #procs",
        procDist_[nprocs] == numGlobalParts, COMPLEX_ASSERTION, comm_);
    }
    else{
      env_->globalBugAssertion(__FILE__, __LINE__,
        "should never get here", 1, COMPLEX_ASSERTION, comm_);
    }
  }
}
 
// Remap a new part assignment vector for maximum overlap with an input
// part assignment.
//
// Assumptions for this version:
//   input part assignment == processor rank for every local object.
//   assuming nGlobalParts_ <= num ranks
// TODO:  Write a version that takes the input part number as input;
//        this change requires input parts in adapters to be provided in
//        the Adapter.
// TODO:  For repartitioning, compare to old remapping results; see Zoltan1.
 
template <typename Adapter>
void PartitioningSolution<Adapter>::RemapParts()
{
  size_t len = parts_.size();
 
  part_t me = comm_->getRank();
  int np = comm_->getSize();
 
  if (np < nGlobalParts_) {
    if (me == 0)
      std::cout << "Remapping not yet supported for "
           << "num_global_parts " << nGlobalParts_
           << " > num procs " << np << std::endl;
    return;
  }
  // Build edges of a bipartite graph with np + nGlobalParts_ vertices,
  // and edges between a process vtx and any parts to which that process'
  // objects are assigned.
  // Weight edge[parts_[i]] by the number of objects that are going from
  // this rank to parts_[i].
  // We use a std::map, assuming the number of unique parts in the parts_ array
  // is small to keep the binary search efficient.
  // TODO We use the count of objects to move; should change to SIZE of objects
  // to move; need SIZE function in Adapter.
 
  std::map<part_t, long> edges;
  long lstaying = 0;  // Total num of local objects staying if we keep the
                      // current mapping. TODO:  change to SIZE of local objs
  long gstaying = 0;  // Total num of objects staying in the current partition
 
  for (size_t i = 0; i < len; i++) {
    edges[parts_[i]]++;                // TODO Use obj size instead of count
    if (parts_[i] == me) lstaying++;    // TODO Use obj size instead of count
  }
 
  Teuchos::reduceAll<int, long>(*comm_, Teuchos::REDUCE_SUM, 1,
                                &lstaying, &gstaying);
//TODO  if (gstaying == Adapter::getGlobalNumObjs()) return;  // Nothing to do
 
  part_t *remap = NULL;
 
  int nedges = edges.size();
 
  // Gather the graph to rank 0.
  part_t tnVtx = np + nGlobalParts_;  // total # vertices
  int *idx = NULL;    // Pointer index into graph adjacencies
  int *sizes = NULL;  // nedges per rank
  if (me == 0) {
    idx = new int[tnVtx+1];
    sizes = new int[np];
    sizes[0] = nedges;
  }
  if (np > 1)
    Teuchos::gather<int, int>(&nedges, 1, sizes, 1, 0, *comm_);
 
  // prefix sum to build the idx array
  if (me == 0) {
    idx[0] = 0;
    for (int i = 0; i < np; i++)
      idx[i+1] = idx[i] + sizes[i];
  }
 
  // prepare to send edges
  int cnt = 0;
  part_t *bufv = NULL;
  long *bufw = NULL;
  if (nedges) {
    bufv = new part_t[nedges];
    bufw = new long[nedges];
    // Create buffer with edges (me, part[i]) and weight edges[parts_[i]].
    for (typename std::map<part_t, long>::iterator it = edges.begin();
         it != edges.end(); it++) {
      bufv[cnt] = it->first;  // target part
      bufw[cnt] = it->second; // weight
      cnt++;
    }
  }
 
  // Prepare to receive edges on rank 0
  part_t *adj = NULL;
  long *wgt = NULL;
  if (me == 0) {
//SYM    adj = new part_t[2*idx[np]];  // need 2x space to symmetrize later
//SYM    wgt = new long[2*idx[np]];  // need 2x space to symmetrize later
    adj = new part_t[idx[np]];
    wgt = new long[idx[np]];
  }
 
  Teuchos::gatherv<int, part_t>(bufv, cnt, adj, sizes, idx, 0, *comm_);
  Teuchos::gatherv<int, long>(bufw, cnt, wgt, sizes, idx, 0, *comm_);
  delete [] bufv;
  delete [] bufw;
 
  // Now have constructed graph on rank 0.
  // Call the matching algorithm
 
  int doRemap;
  if (me == 0) {
    // We have the "LHS" vertices of the bipartite graph; need to create
    // "RHS" vertices.
    for (int i = 0; i < idx[np]; i++) {
      adj[i] += np;  // New RHS vertex number; offset by num LHS vertices
    }
 
    // Build idx for RHS vertices
    for (part_t i = np; i < tnVtx; i++) {
      idx[i+1] = idx[i];  // No edges for RHS vertices
    }
 
#ifdef KDDKDD_DEBUG
    std::cout << "IDX ";
    for (part_t i = 0; i <= tnVtx; i++) std::cout << idx[i] << " ";
    std::cout << std::endl;
 
    std::cout << "ADJ ";
    for (part_t i = 0; i < idx[tnVtx]; i++) std::cout << adj[i] << " ";
    std::cout << std::endl;
 
    std::cout << "WGT ";
    for (part_t i = 0; i < idx[tnVtx]; i++) std::cout << wgt[i] << " ";
    std::cout << std::endl;
#endif
 
    // Perform matching on the graph
    part_t *match = new part_t[tnVtx];
    for (part_t i = 0; i < tnVtx; i++) match[i] = i;
    part_t nmatches =
             Zoltan2::GreedyMWM<part_t, long>(idx, adj, wgt, tnVtx, match);
 
#ifdef KDDKDD_DEBUG
    std::cout << "After matching:  " << nmatches << " found" << std::endl;
    for (part_t i = 0; i < tnVtx; i++)
      std::cout << "match[" << i << "] = " << match[i]
           << ((match[i] != i &&
               (i < np && match[i] != i+np))
                  ? " *" : " ")
           << std::endl;
#endif
 
    // See whether there were nontrivial changes in the matching.
    bool nontrivial = false;
    if (nmatches) {
      for (part_t i = 0; i < np; i++) {
        if ((match[i] != i) && (match[i] != (i+np))) {
          nontrivial = true;
          break;
        }
      }
    }
 
    // Process the matches
    if (nontrivial) {
      remap = new part_t[nGlobalParts_];
      for (part_t i = 0; i < nGlobalParts_; i++) remap[i] = -1;
 
      bool *used = new bool[np];
      for (part_t i = 0; i < np; i++) used[i] = false;
 
      // First, process all matched parts
      for (part_t i = 0; i < nGlobalParts_; i++) {
        part_t tmp = i + np;
        if (match[tmp] != tmp) {
          remap[i] = match[tmp];
          used[match[tmp]] = true;
        }
      }
 
      // Second, process unmatched parts; keep same part number if possible
      for (part_t i = 0; i < nGlobalParts_; i++) {
        if (remap[i] > -1) continue;
        if (!used[i]) {
          remap[i] = i;
          used[i] = true;
        }
      }
 
      // Third, process unmatched parts; give them the next unused part
      for (part_t i = 0, uidx = 0; i < nGlobalParts_; i++) {
        if (remap[i] > -1) continue;
        while (used[uidx]) uidx++;
        remap[i] = uidx;
        used[uidx] = true;
      }
      delete [] used;
    }
    delete [] match;
 
#ifdef KDDKDD_DEBUG
    std::cout << "Remap vector: ";
    for (part_t i = 0; i < nGlobalParts_; i++) std::cout << remap[i] << " ";
    std::cout << std::endl;
#endif
 
    long newgstaying = measure_stays(remap, idx, adj, wgt,
                                                      nGlobalParts_, np);
    doRemap = (newgstaying > gstaying);
    std::cout << "gstaying " << gstaying << " measure(input) "
         << measure_stays(NULL, idx, adj, wgt, nGlobalParts_, np)
         << " newgstaying " << newgstaying
         << " nontrivial " << nontrivial
         << " doRemap " << doRemap << std::endl;
  }
  delete [] idx;
  delete [] sizes;
  delete [] adj;
  delete [] wgt;
 
  Teuchos::broadcast<int, int>(*comm_, 0, 1, &doRemap);
 
  if (doRemap) {
    if (me != 0) remap = new part_t[nGlobalParts_];
    Teuchos::broadcast<int, part_t>(*comm_, 0, nGlobalParts_, remap);
    for (size_t i = 0; i < len; i++) {
      parts_[i] = remap[parts_[i]];
    }
  }
 
  delete [] remap;  // TODO May want to keep for repartitioning as in Zoltan
}
 
 
}  // namespace Zoltan2
 
#endif