// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2023 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
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// modification, are permitted provided that the following conditions are met:
//
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//   this list of conditions and the following disclaimer.
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//   this list of conditions and the following disclaimer in the documentation
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_SINGLE_LINKAGE_CLUSTERING_H_
#define CERES_INTERNAL_SINGLE_LINKAGE_CLUSTERING_H_

#include "absl/container/flat_hash_map.h"
#include "ceres/graph.h"
#include "ceres/internal/disable_warnings.h"
#include "ceres/internal/export.h"

namespace ceres::internal {

struct SingleLinkageClusteringOptions {
  // Graph edges with edge weight less than min_similarity are ignored
  // during the clustering process.
  double min_similarity = 0.99;
};

// Compute a partitioning of the vertices of the graph using the
// single linkage clustering algorithm. Edges with weight less than
// SingleLinkageClusteringOptions::min_similarity will be ignored.
//
// membership upon return will contain a mapping from the vertices of
// the graph to an integer indicating the identity of the cluster that
// it belongs to.
//
// The return value of this function is the number of clusters
// identified by the algorithm.
CERES_NO_EXPORT int ComputeSingleLinkageClustering(
    const SingleLinkageClusteringOptions& options,
    const WeightedGraph<int>& graph,
    absl::flat_hash_map<int, int>* membership);

}  // namespace ceres::internal

#include "ceres/internal/reenable_warnings.h"

#endif  // CERES_INTERNAL_SINGLE_LINKAGE_CLUSTERING_H_