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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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/* 深度優先走訪輔助函式 */
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void DFS(GraphAdjList graph, HashSet<Vertex> visited, List<Vertex> res, Vertex vet) {
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res.Add(vet); // 記錄訪問頂點
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visited.Add(vet); // 標記該頂點已被訪問
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// 走訪該頂點的所有鄰接頂點
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foreach (Vertex adjVet in graph.adjList[vet]) {
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if (visited.Contains(adjVet)) {
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continue; // 跳過已被訪問的頂點
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}
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// 遞迴訪問鄰接頂點
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DFS(graph, visited, res, adjVet);
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}
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}
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/* 深度優先走訪 */
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// 使用鄰接表來表示圖，以便獲取指定頂點的所有鄰接頂點
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List<Vertex> GraphDFS(GraphAdjList graph, Vertex startVet) {
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// 頂點走訪序列
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List<Vertex> res = [];
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// 雜湊集合，用於記錄已被訪問過的頂點
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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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/* 初始化無向圖 */
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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初始化後，圖為");
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graph.Print();
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/* 深度優先走訪 */
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List<Vertex> res = GraphDFS(graph, v[0]);
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Console.WriteLine("\n深度優先走訪（DFS）頂點序列為");
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Console.WriteLine(string.Join(" ", Vertex.VetsToVals(res)));
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}
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}
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