65 lines
2.2 KiB
Kotlin
65 lines
2.2 KiB
Kotlin
/*
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* MIT License
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*
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* Copyright (c) 2019 norangebit
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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*/
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package it.norangeb.algorithms.graph.operations
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import it.norangeb.algorithms.graph.DirectedGraph
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import it.norangeb.algorithms.graph.UndirectedGraph
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class StronglyConnectedComponents(graph: DirectedGraph) {
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private val graphInfo = Array(graph.vertexNumber()) { VertexInfo() }
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private var label = 0
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init {
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DepthFirstOrder(graph.reverse())
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.reversePostOrder()
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.forEach {
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if (!graphInfo[it].isVisited)
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dfs(graph, it, label++)
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}
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}
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private fun dfs(graph: UndirectedGraph, vertex: Int, label: Int) {
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graphInfo[vertex] = VertexInfo(true, label)
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graph.adjacentVertex(vertex)
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.forEach {
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if (!graphInfo[it].isVisited)
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dfs(graph, it, label)
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}
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}
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fun count() = label
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fun component(vertex: Int) = graphInfo[vertex].label
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fun stronglyConnected(firstVertex: Int, secondVertex: Int) =
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component(firstVertex) == component(secondVertex)
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private data class VertexInfo(
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var isVisited: Boolean = false,
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var label: Int = -1
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)
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} |