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* Revised the book * Update the book with the second revised edition * Revise base on the manuscript of the first edition
58 lines
2 KiB
C#
58 lines
2 KiB
C#
/**
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* File: graph_bfs.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_bfs {
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/* 广度优先遍历 */
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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> GraphBFS(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 = [startVet];
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// 队列用于实现 BFS
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Queue<Vertex> que = new();
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que.Enqueue(startVet);
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// 以顶点 vet 为起点，循环直至访问完所有顶点
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while (que.Count > 0) {
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Vertex vet = que.Dequeue(); // 队首顶点出队
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res.Add(vet); // 记录访问顶点
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foreach (Vertex adjVet in graph.adjList[vet]) {
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if (visited.Contains(adjVet)) {
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continue; // 跳过已被访问的顶点
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}
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que.Enqueue(adjVet); // 只入队未访问的顶点
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visited.Add(adjVet); // 标记该顶点已被访问
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}
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}
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// 返回顶点遍历序列
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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, 7, 8, 9]);
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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[1], v[4]], [v[2], v[5]], [v[3], v[4]],
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[v[3], v[6]], [v[4], v[5]], [v[4], v[7]],
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[v[5], v[8]], [v[6], v[7]], [v[7], v[8]]
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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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/* 广度优先遍历 */
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List<Vertex> res = GraphBFS(graph, v[0]);
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Console.WriteLine("\n广度优先遍历（BFS）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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