/*
* function TreeNode(x) {
* this.val = x;
* this.left = null;
* this.right = null;
* }
*/
/**
*
* @param root TreeNode类
* @return int整型
*/
function maxDepth( root ) {
// write code here
return dfs(root)
}
function dfs(root){
if(root===null){
return 0
}
let left = dfs(root.left)
let right = dfs(root.right)
return Math.max(left+1,right+1)
}
module.exports = {
maxDepth : maxDepth
};