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59 lines
2 KiB
C++
59 lines
2 KiB
C++
/**
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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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/* 廣度優先走訪 */
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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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vector<Vertex *> graphBFS(GraphAdjList &graph, Vertex *startVet) {
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// 頂點走訪序列
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vector<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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unordered_set<Vertex *> visited = {startVet};
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// 佇列用於實現 BFS
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queue<Vertex *> que;
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que.push(startVet);
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// 以頂點 vet 為起點，迴圈直至訪問完所有頂點
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while (!que.empty()) {
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Vertex *vet = que.front();
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que.pop(); // 佇列首頂點出隊
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res.push_back(vet); // 記錄訪問頂點
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// 走訪該頂點的所有鄰接頂點
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for (auto adjVet : graph.adjList[vet]) {
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if (visited.count(adjVet))
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continue; // 跳過已被訪問的頂點
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que.push(adjVet); // 只入列未訪問的頂點
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visited.emplace(adjVet); // 標記該頂點已被訪問
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}
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}
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// 返回頂點走訪序列
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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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/* 初始化無向圖 */
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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初始化後，圖為\\n";
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graph.print();
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/* 廣度優先走訪 */
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vector<Vertex *> res = graphBFS(graph, v[0]);
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cout << "\n廣度優先走訪（BFS）頂點序列為" << endl;
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printVector(vetsToVals(res));
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// 釋放記憶體
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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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