二叉树深度优先搜索（DFS）- Java

关注

原创最新推荐文章于 2026-03-22 00:13:00 发布 341 阅读 AI 写同款· GEO 优化 ›

遍历二叉树的深度优先搜索(DFS)和广度优先搜索(BFS)的Java编程实现 深度优先搜索是一种先根遍历的算法，它从根节点开始，递归地访问每个节点的左子树和右子树。以上代码实现了二叉树的深度优先搜索和广度优先搜索算法。使用这两种算法可以遍历二叉树并访问每个节点。广度优先搜索是一种按层遍历的算法，它从根节点开始，逐层地访问每个节点。深度优先搜索和广度优先搜索是常用的二叉树遍历算法。本文将介绍如何使用Java编程语言实现这两种遍历算法。函数，并传入二叉树的根节点来执行相应的遍历算法。希望本文对你理解和实现二叉树遍历算法有所帮助！阅读详情

public class DFSMain {

    public static void main(String[] args) {
		// 创建二叉树
        TreeNode n11 = new TreeNode(11);
        TreeNode n10 = new TreeNode(10);
        TreeNode n9 = new TreeNode(9);
        TreeNode n8 = new TreeNode(8);
        TreeNode n7 = new TreeNode(7, n11, null);
        TreeNode n6 = new TreeNode(6, n9, n10);
        TreeNode n5 = new TreeNode(5);
        TreeNode n4 = new TreeNode(4, null, n8);
        TreeNode n3 = new TreeNode(3, n6, n7);
        TreeNode n2 = new TreeNode(2, n4, n5);
        TreeNode n1 = new TreeNode(1, n2, n3);

        System.out.println(recursive(n1));  // [1, 2, 4, 8, 5, 3, 6, 9, 10, 7, 11]
        System.out.println(unRecursive(n1));    // [1, 2, 4, 8, 5, 3, 6, 9, 10, 7, 11]
    }


    /**
     * 递归
     */
    public static List<Integer> recursive(TreeNode root) {
        List<Integer> list = new ArrayList<>();
        dfs(root, list);
        return list;
    }

    public static void dfs(TreeNode root, List<Integer> list) {
        if (root == null) {
            return;
        }

        list.add(root.val);
        // 左递归
        dfs(root.left, list);
        // 右递归
        dfs(root.right, list);
    }

    /**
     * 非递归
     */
    public static List<Integer> unRecursive(TreeNode root) {
        List<Integer> list = new ArrayList<>();
        Stack<TreeNode> stack = new Stack<>();

        if (root == null) {
            return list;
        }

        stack.push(root);

        while (!stack.isEmpty()) {
            // 弹栈
            TreeNode node = stack.pop();
            // 右子树先入栈
            if (node.right != null) {
                stack.push(node.right);
            }
            // 左子树后入栈
            if (node.left != null) {
                stack.push(node.left);
            }

            list.add(node.val);
        }

        return list;
    }

}

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;

    TreeNode(int val, TreeNode left, TreeNode right) {
        this.val = val;
        this.left = left;
        this.right = right;
    }

    TreeNode(int val) {
        this.val = val;
    }

    @Override
    public String toString() {
        return "TreeNode{" +
                "val=" + val +
                ", left=" + left +
                ", right=" + right +
                '}';
    }
}