hello-algo/codes/java/chapter_graph/graph_dfs.java

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/**
* File: graph_dfs.java
* Created Time: 2023-02-12
* Author: Krahets (krahets@163.com)
*/
package chapter_graph;
import java.util.*;
import utils.*;
public class graph_dfs {
/* 深度优先遍历 DFS 辅助函数 */
static void dfs(GraphAdjList graph, Set<Vertex> visited, List<Vertex> res, Vertex vet) {
res.add(vet); // 记录访问顶点
visited.add(vet); // 标记该顶点已被访问
// 遍历该顶点的所有邻接顶点
for (Vertex adjVet : graph.adjList.get(vet)) {
if (visited.contains(adjVet))
continue; // 跳过已被访问的顶点
// 递归访问邻接顶点
dfs(graph, visited, res, adjVet);
}
}
/* 深度优先遍历 DFS */
// 使用邻接表来表示图,以便获取指定顶点的所有邻接顶点
static List<Vertex> graphDFS(GraphAdjList graph, Vertex startVet) {
// 顶点遍历序列
List<Vertex> res = new ArrayList<>();
// 哈希表,用于记录已被访问过的顶点
Set<Vertex> visited = new HashSet<>();
dfs(graph, visited, res, startVet);
return res;
}
public static void main(String[] args) {
/* 初始化无向图 */
Vertex[] v = Vertex.valsToVets(new int[] { 0, 1, 2, 3, 4, 5, 6 });
Vertex[][] edges = { { v[0], v[1] }, { v[0], v[3] }, { v[1], v[2] },
{ v[2], v[5] }, { v[4], v[5] }, { v[5], v[6] } };
GraphAdjList graph = new GraphAdjList(edges);
System.out.println("\n初始化后图为");
graph.print();
/* 深度优先遍历 DFS */
List<Vertex> res = graphDFS(graph, v[0]);
System.out.println("\n深度优先遍历DFS顶点序列为");
System.out.println(Vertex.vetsToVals(res));
}
}