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/**
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* File: graph_dfs.swift
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* Created Time: 2023-02-21
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* Author: nuomi1 (nuomi1@qq.com)
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*/
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import graph_adjacency_list_target
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import utils
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/* 深度优先遍历 DFS 辅助函数 */
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func dfs(graph: GraphAdjList, visited: inout Set<Vertex>, res: inout [Vertex], vet: Vertex) {
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res.append(vet) // 记录访问顶点
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visited.insert(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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for 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: graph, visited: &visited, res: &res, vet: 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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func graphDFS(graph: GraphAdjList, startVet: Vertex) -> [Vertex] {
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// 顶点遍历序列
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var res: [Vertex] = []
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// 哈希表，用于记录已被访问过的顶点
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var visited: Set<Vertex> = []
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dfs(graph: graph, visited: &visited, res: &res, vet: startVet)
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return res
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}
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@main
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enum GraphDFS {
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/* Driver Code */
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static func main() {
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/* 初始化无向图 */
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let v = Vertex.valsToVets(vals: [0, 1, 2, 3, 4, 5, 6])
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let edges = [
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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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let graph = GraphAdjList(edges: edges)
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print("\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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let res = graphDFS(graph: graph, startVet: v[0])
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print("\n深度优先遍历（DFS）顶点序列为")
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print(Vertex.vetsToVals(vets: res))
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}
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}
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