leetcode 104. 二叉树的最大深度 js实现

    3
   / \
  9  20
    /  \
   15   7

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
var maxDepth = function(root) {
    if(!root){
        return 0;
    }
    let leftDepth = maxDepth(root.left);
    let rightDepth = maxDepth(root.right);
    return Math.max(leftDepth,rightDepth)+1;
};