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/**
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* File: graph_adjacency_list.dart
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* Created Time: 2023-05-15
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* Author: liuyuxin (gvenusleo@gmail.com)
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*/
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import '../utils/vertex.dart';
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/* 基于邻接表实现的无向图类 */
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class GraphAdjList {
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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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Map<Vertex, List<Vertex>> adjList = {};
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/* 构造方法 */
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GraphAdjList(List<List<Vertex>> edges) {
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for (List<Vertex> 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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int size() {
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return adjList.length;
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}
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/* 添加边 */
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void addEdge(Vertex vet1, Vertex vet2) {
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if (!adjList.containsKey(vet1) ||
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!adjList.containsKey(vet2) ||
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vet1 == vet2) {
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throw ArgumentError;
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}
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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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void removeEdge(Vertex vet1, Vertex vet2) {
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if (!adjList.containsKey(vet1) ||
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!adjList.containsKey(vet2) ||
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vet1 == vet2) {
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throw ArgumentError;
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}
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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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void addVertex(Vertex vet) {
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if (adjList.containsKey(vet)) return;
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// 在邻接表中添加一个新链表
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adjList[vet] = [];
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}
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/* 删除顶点 */
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void removeVertex(Vertex vet) {
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if (!adjList.containsKey(vet)) {
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throw ArgumentError;
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}
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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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adjList.forEach((key, value) {
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value.remove(vet);
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});
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}
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/* 打印邻接表 */
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void printAdjList() {
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print("邻接表 =");
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adjList.forEach((key, value) {
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List<int> tmp = [];
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for (Vertex vertex in value) {
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tmp.add(vertex.val);
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}
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print("${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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void main() {
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/* 初始化无向图 */
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List<Vertex> v = Vertex.valsToVets([1, 3, 2, 5, 4]);
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List<List<Vertex>> edges = [
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[v[0], v[1]],
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[v[0], v[3]],
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[v[1], v[2]],
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[v[2], v[3]],
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[v[2], v[4]],
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[v[3], v[4]],
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];
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GraphAdjList graph = GraphAdjList(edges);
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print("\n初始化后，图为");
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graph.printAdjList();
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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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print("\n添加边 1-2 后，图为");
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graph.printAdjList();
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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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print("\n删除边 1-3 后，图为");
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graph.printAdjList();
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/* 添加顶点 */
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Vertex v5 = Vertex(6);
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graph.addVertex(v5);
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print("\n添加顶点 6 后，图为");
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graph.printAdjList();
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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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print("\n删除顶点 3 后，图为");
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graph.printAdjList();
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}
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