每天过20个单词，1道leetcode，写一小段代码（有趣的）（需求中的或者自己写着玩的 如canvas动画 小游戏）
leetcode #199
Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.
/**
* Definition for a binary tree node.
* function TreeNode(val) {
* this.val = val;
* this.left = this.right = null;
* }
*/
/**
* @param {TreeNode} root
* @return {number[]}
*/
var rightSideView = function(root) {
let stack = [root];
let cur = root;
let last = root;
let result = [];
while(stack.length&&root){
cur = stack.pop();
if(cur.left){
stack.unshift(cur.left);
}
if(cur.right){
stack.unshift(cur.right);
}
if(cur === last){
result.push(cur.val);
last = stack[0];
}
}
return result;
};
跑出来是最慢的里面的最慢的，慢到分布图里显示不到。等我学会了优化这种东西，就要飞起了。
