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/**
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* File: graph_bfs.cpp
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* Created Time: 2023-03-02
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* Author: Krahets (krahets@163.com)
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*/
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#include "../utils/common.hpp"
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#include "./graph_adjacency_list.cpp"
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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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vector<Vertex *> graphBFS(GraphAdjList &graph, Vertex *startVet) {
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// 顶点遍历序列
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vector<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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unordered_set<Vertex *> visited = {startVet};
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// 队列用于实现 BFS
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queue<Vertex *> que;
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que.push(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.empty()) {
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Vertex *vet = que.front();
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que.pop(); // 队首顶点出队
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res.push_back(vet); // 记录访问顶点
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// 遍历该顶点的所有邻接顶点
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for (auto adjVet : graph.adjList[vet]) {
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if (visited.count(adjVet))
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continue; // 跳过已被访问的顶点
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que.push(adjVet); // 只入队未访问的顶点
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visited.emplace(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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/* Driver Code */
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int main() {
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/* 初始化无向图 */
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vector<Vertex *> v = valsToVets({0, 1, 2, 3, 4, 5, 6, 7, 8, 9});
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vector<vector<Vertex *>> edges = {{v[0], v[1]}, {v[0], v[3]}, {v[1], v[2]}, {v[1], v[4]},
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{v[2], v[5]}, {v[3], v[4]}, {v[3], v[6]}, {v[4], v[5]},
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{v[4], v[7]}, {v[5], v[8]}, {v[6], v[7]}, {v[7], v[8]}};
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GraphAdjList graph(edges);
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cout << "\n初始化后，图为\\n";
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graph.print();
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/* 广度优先遍历 */
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vector<Vertex *> res = graphBFS(graph, v[0]);
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cout << "\n广度优先遍历（BFS）顶点序列为" << endl;
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printVector(vetsToVals(res));
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// 释放内存
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for (Vertex *vet : v) {
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delete vet;
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}
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return 0;
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}
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