202. Happy Number

Write an algorithm to determine if a number is “happy”.

A happy number is a number defined by the following process: Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 (where it will stay), or it loops endlessly in a cycle which does not include 1. Those numbers for which this process ends in 1 are happy numbers.

这个题目是做了蛮久的，现在看来逻辑搞清楚的话其实很简单了。
题目要求说最终结果不是1的就是false，出现循环的也是false，循环其实不是很好界定，因为并不知道会从第几个数字开始循环。所以我就给了一个最多计算的次数 50. 够多了吧》》》超过50说明肯定循环了。

/** * @param {number} n * @return {boolean} */var isHappy = function(n) {    var time=0;    while(n>0 && time<50){        time++;        var sum=0;        while(n){            sum+=(n%10)*(n%10);            n=parseInt(n/10);        }        n=sum;        if(n==1)return true;    }    return false;};