图的深度优先遍历

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Stack;

/**
 * 图的深度优先遍历
 */
public class DepthFirst {

    public static void df(Node node) {
        if (node == null) {
            return;
        }
        Stack<Node> stack = new Stack<>();
        HashSet<Node> set = new HashSet<>();
        stack.add(node);
        set.add(node);
        System.out.println(node.value);
        while (!stack.isEmpty()) {
            Node cur = stack.pop();
            for (Node next : cur.nexts) {
                if (!set.contains(next)) {
                    stack.push(cur);
                    stack.push(next);
                    set.add(next);
                    System.out.println(next.value);
                    break;
                }
            }
        }
    }

    class Graph {

        public HashMap<Integer, Node> nodes;

        public HashSet<Edge> edges;

        public Graph() {
            nodes = new HashMap<>();
            edges = new HashSet<>();
        }

    }

    class Node {

        public int value;

        public int in;

        public int out;

        public ArrayList<Node> nexts;

        public ArrayList<Edge> edges;

        public Node(int value) {
            this.value = value;
            nexts = new ArrayList<>();
            edges = new ArrayList<>();
        }

    }

    class Edge {

        // 权重
        public int weight;

        public Node from;

        public Node to;

        public Edge(int weight, Node from, Node to) {
            this.weight = weight;
            this.from = from;
            this.to = to;
        }

    }

}

/* 如有意见或建议，欢迎评论区留言；如发现代码有误，欢迎批评指正 */