# C++ Reference: class MergingPartition

Note: This documentation is automatically generated.

Partition class that supports incremental merging, using the union-find algorithm (see http://en.wikipedia.org/wiki/Disjoint-set_data_structure).Method | |
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`DebugString` | Return type: Dump all components, with nodes sorted within each part and parts sorted lexicographically. Eg. "0 1 3 4 | 2 5 | 6 7 8". |

`FillEquivalenceClasses` | Return type: Arguments: Output the whole partition as node equivalence classes: if there are K parts and N nodes, node_equivalence_classes[i] will contain the part index (a number in 0..K-1) of node #i. Parts will be sorted by their first node (i.e. node 0 will always be in part 0; then the next node that isn't in part 0 will be in part 1, and so on). Returns the number K of classes. |

`GetRoot` | Return type: Arguments: FOR DEBUGGING OR SPECIAL "CONST" ACCESS ONLY: Find the root of the union-find tree with leaf 'node', i.e. its representative node, but don't use path compression. The amortized complexity can be as bad as log(N), as opposed to the version using path compression. |

`GetRootAndCompressPath` | Return type: Arguments: Get the representative of "node" (a node in the same equivalence class, which will also be returned for any other "node" in the same class). The complexity if the same as MergePartsOf(). |

`KeepOnlyOneNodePerPart` | Return type: Arguments: Specialized reader API: prunes "nodes" to only keep at most one node per part: any node which is in the same part as an earlier node will be pruned. |

`MergePartsOf` | Return type: Arguments: Complexity: amortized O(Ackermann⁻¹(N)) -- which is essentially O(1) -- where N is the number of nodes. Return value: If this merge caused a representative node (of either node1 or node2) to stop being a representative (because only one can remain); this method returns that removed representative. Otherwise it returns -1. Details: a smaller part will always be merged onto a larger one. Upons ties, the smaller representative becomes the overall representative. |

`MergingPartition` | At first, all nodes are in their own singleton part. |

`MergingPartition` | Return type: Arguments: |

`NumNodes` | Return type: |

`NumNodesInSamePartAs` | Return type: Arguments: |

`Reset` | Return type: Arguments: |

`ResetNode` | Return type: Arguments: Advanced usage: sets 'node' to be in its original singleton. All nodes who may point to 'node' as a parent will remain in an inconsistent state. This can be used to reinitialize a MergingPartition that has been sparsely modified in O(|modifications|). CRASHES IF USED INCORRECTLY. |