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/**
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* File: graph_adjacency_list.kt
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* Created Time: 2024-01-25
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* Author: curtishd (1023632660@qq.com)
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*/
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package chapter_graph
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import utils.Vertex
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/* 基于邻接表实现的无向图类 */
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class GraphAdjList(edges: Array<Array<Vertex?>>) {
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// 邻接表，key：顶点，value：该顶点的所有邻接顶点
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val adjList = HashMap<Vertex, MutableList<Vertex>>()
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/* 构造方法 */
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init {
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// 添加所有顶点和边
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for (edge in edges) {
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addVertex(edge[0]!!)
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addVertex(edge[1]!!)
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addEdge(edge[0]!!, edge[1]!!)
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}
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}
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/* 获取顶点数量 */
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fun size(): Int {
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return adjList.size
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}
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/* 添加边 */
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fun addEdge(vet1: Vertex, vet2: Vertex) {
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if (!adjList.containsKey(vet1) || !adjList.containsKey(vet2) || vet1 == vet2)
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throw IllegalArgumentException()
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// 添加边 vet1 - vet2
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adjList[vet1]?.add(vet2)
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adjList[vet2]?.add(vet1)
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}
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/* 删除边 */
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fun removeEdge(vet1: Vertex, vet2: Vertex) {
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if (!adjList.containsKey(vet1) || !adjList.containsKey(vet2) || vet1 == vet2)
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throw IllegalArgumentException()
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// 删除边 vet1 - vet2
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adjList[vet1]?.remove(vet2)
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adjList[vet2]?.remove(vet1)
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}
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/* 添加顶点 */
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fun addVertex(vet: Vertex) {
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if (adjList.containsKey(vet))
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return
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// 在邻接表中添加一个新链表
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adjList[vet] = mutableListOf()
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}
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/* 删除顶点 */
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fun removeVertex(vet: Vertex) {
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if (!adjList.containsKey(vet))
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throw IllegalArgumentException()
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// 在邻接表中删除顶点 vet 对应的链表
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adjList.remove(vet)
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// 遍历其他顶点的链表，删除所有包含 vet 的边
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for (list in adjList.values) {
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list.remove(vet)
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}
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}
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/* 打印邻接表 */
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fun print() {
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println("邻接表 =")
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for (pair in adjList.entries) {
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val tmp = mutableListOf<Int>()
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for (vertex in pair.value) {
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tmp.add(vertex._val)
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}
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println("${pair.key._val}: $tmp,")
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}
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}
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}
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/* Driver Code */
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fun main() {
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/* 初始化无向图 */
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val v = Vertex.valsToVets(intArrayOf(1, 3, 2, 5, 4))
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val edges = arrayOf(
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arrayOf(v[0], v[1]),
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arrayOf(v[0], v[3]),
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arrayOf(v[1], v[2]),
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arrayOf(v[2], v[3]),
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arrayOf(v[2], v[4]),
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arrayOf(v[3], v[4])
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)
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val graph = GraphAdjList(edges)
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println("\n初始化后，图为")
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graph.print()
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/* 添加边 */
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// 顶点 1, 2 即 v[0], v[2]
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graph.addEdge(v[0]!!, v[2]!!)
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println("\n添加边 1-2 后，图为")
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graph.print()
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/* 删除边 */
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// 顶点 1, 3 即 v[0], v[1]
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graph.removeEdge(v[0]!!, v[1]!!)
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println("\n删除边 1-3 后，图为")
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graph.print()
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/* 添加顶点 */
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val v5 = Vertex(6)
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graph.addVertex(v5)
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println("\n添加顶点 6 后，图为")
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graph.print()
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/* 删除顶点 */
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// 顶点 3 即 v[1]
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graph.removeVertex(v[1]!!)
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println("\n删除顶点 3 后，图为")
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graph.print()
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} |
