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/**
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* File: graph_dfs.cs
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* Created Time: 2023-03-08
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* Author: hpstory (hpstory1024@163.com)
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*/
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namespace hello_algo.chapter_graph;
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public class graph_dfs {
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/* 深度优先遍历 DFS 辅助函数 */
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void DFS(GraphAdjList graph, HashSet<Vertex> visited, List<Vertex> res, Vertex vet) {
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res.Add(vet); // 记录访问顶点
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visited.Add(vet); // 标记该顶点已被访问
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// 遍历该顶点的所有邻接顶点
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foreach (Vertex adjVet in graph.adjList[vet]) {
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if (visited.Contains(adjVet)) {
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continue; // 跳过已被访问过的顶点
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}
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// 递归访问邻接顶点
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DFS(graph, visited, res, adjVet);
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}
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}
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/* 深度优先遍历 DFS */
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// 使用邻接表来表示图，以便获取指定顶点的所有邻接顶点
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List<Vertex> GraphDFS(GraphAdjList graph, Vertex startVet) {
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// 顶点遍历序列
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List<Vertex> res = [];
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// 哈希表，用于记录已被访问过的顶点
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HashSet<Vertex> visited = [];
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DFS(graph, visited, res, startVet);
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return res;
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}
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[Test]
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public void Test() {
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/* 初始化无向图 */
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Vertex[] v = Vertex.ValsToVets([0, 1, 2, 3, 4, 5, 6]);
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Vertex[][] edges =
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[
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[v[0], v[1]], [v[0], v[3]], [v[1], v[2]],
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[v[2], v[5]], [v[4], v[5]], [v[5], v[6]],
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];
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GraphAdjList graph = new(edges);
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Console.WriteLine("\n初始化后，图为");
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graph.Print();
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/* 深度优先遍历 DFS */
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List<Vertex> res = GraphDFS(graph, v[0]);
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Console.WriteLine("\n深度优先遍历（DFS）顶点序列为");
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Console.WriteLine(string.Join(" ", Vertex.VetsToVals(res)));
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}
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}
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