README.md

Maximum Depth of Binary Tree

Description

Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

Tags: Tree, Depth-first Search

思路

题意是找到二叉树的最大深度，很明显，深搜即可，每深入一次节点加一即可，然后取左右子树的最大深度。

Java:

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
 class Solution {
     public int maxDepth(TreeNode root) {
         if (root == null) return 0;
         return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
     }
 }

kotlin(212ms/100.00%):

class Solution {
    fun maxDepth(root: TreeNode?): Int {
        if (root == null) return 0
        if (root.left == null) return 1 + maxDepth(root.right)
        if (root.right == null) return 1 + maxDepth(root.left)
        return Math.max(1 + maxDepth(root.left), 1 + maxDepth(root.right))
    }
}

JavaScript：

var maxDepth = function(root) {
    if (root == null) return 0;
     return 1 + Math.max(maxDepth(root.left), maxDepth(root.right));
};

结语

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