[Leetcode]104. Maximum Depth of Binary Tree

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.

思路：只需要简单的递归就好了，如果到达null了就返回高度为0；

/**
 * 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) {
        int lHeight = 0,rHeight = 0;
        if(root==null)
            return 0;
        else {
            lHeight = maxDepth(root.left);              //递归求左树的深度
            rHeight = maxDepth(root.right);           //递归求右树的深度
        }
        if (lHeight<rHeight)                                  //因为求的是整棵树的最深深度
            lHeight = rHeight;                                //所以如果左树比右树浅，则令
        return lHeight+1;                                     //lHeight = rHeight，然后返回
    }                                                                 
}