问题描述
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.
Note: A leaf is a node with no children.
Example:
Given binary tree [3,9,20,null,null,15,7],
3
/ \
9 20
/ \
15 7
return depth 3
思路:递归咯,判断每个节点的左子树和右子树的高度
/**
* Definition for a binary tree node.
* function TreeNode(val) {
* this.val = val;
* this.left = this.right = null;
* }
*/
/**
* @param {TreeNode} root
* @return {number}
*/
function depth(root) {
if(root == null) return 0;
return Math.max(depth(root.left), depth(root.right)) + 1
}
var maxDepth = function(root) {
return depth(root)
};