100.相同的树

/*** 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} p* @param {TreeNode} q* @return {boolean}*/
var isSameTree = function(p, q) {if(p===null&&q!==null){return false}if(p!==null&&q===null){return false}if(p===null&&q===null){return true}else{return p.val===q.val&&isSameTree(p.left,q.left) && isSameTree(p.right,q.right)}return isSameTree(p,q)
};