day43（12.24）——leetcode面试经典150

104. 二叉树的最大深度

104. 二叉树的最大深度

又来到了我最难受的dfs了，每次我都觉得dfs特别神奇！！！

题目：

题解：

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

    public int maxDepth(TreeNode root) {
        return dfs(root);
    }
}