104. Maximum Depth of Binary Tree-优快云博客

本文介绍了一种使用递归实现深度优先搜索的方法来解决LeetCode上的一道关于二叉树的问题——求解二叉树的最大深度。通过具体的代码示例展示了如何从根节点开始遍历整个二叉树并计算其深度。

原题链接：https://leetcode.com/problems/maximum-depth-of-binary-tree/description/
这道题目级别为“Easy”，也确实是简单！
不废话，直接使用递归实现深度优先搜索即可：

/**
 * Created by clearbug on 2018/2/26.
 */
public class Solution {

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

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

    public static void main(String[] args) {
        TreeNode root = new TreeNode(1);

        TreeNode rootLeft = new TreeNode(2);
        TreeNode rootRight = new TreeNode(3);
        root.left = rootLeft;
        root.right = rootRight;

        TreeNode leftLeft = new TreeNode(3);
        TreeNode leftRight = null;
        rootLeft.left = leftLeft;
        rootLeft.right = leftRight;

        TreeNode rightLeft = new TreeNode(2);
        TreeNode rightRight = null;
        rootRight.left = rightLeft;
        rootRight.right = rightRight;

        Solution s = new Solution();
        System.out.println(s.maxDepth(root));
    }

    public int maxDepth(TreeNode root) {
        if (root == null) {
            return 0;
        }
        return dfs(root, 1);
    }

    public int dfs(TreeNode node, int currentDepth) {

        int leftDepth = currentDepth, rightDepth = currentDepth;
        if (node.left != null) {
            leftDepth = dfs(node.left, currentDepth + 1);
        }
        if (node.right != null) {
            rightDepth = dfs(node.right, currentDepth + 1);
        }

        return leftDepth > rightDepth ?
                (leftDepth > currentDepth ? leftDepth : currentDepth) :
                (rightDepth > currentDepth ? rightDepth : currentDepth);
    }
}

转载于:https://www.cnblogs.com/optor/p/8538637.html