LeetCode 202 Happy Number

题目：

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.

Example: 19 is a happy number
12 + 92 = 82
82 + 22 = 68
62 + 82 = 100
12 + 02 + 02 =
1
题目链接
题意：

介绍了“happy”数的定义，写一个函数判断所给的数是不是“happy”数。

“happy”数的定义是，把所有位的数求平方和，组成新数，判断是否为1，若为1，则为“happy”数，否则不是，继续循环操作。

写的算法中因为没有确定的界限，所以把计算次数进行约束，假如超过一定次数，则退出循环，这是一种cheat方法，可能是样例比较简单，，，居然给过了。

代码如下：

class Solution {
public:
int plus(int n) {
int temp = 0;
while (n) {
temp += (n%10) * (n%10);
n /= 10;
}
return temp;
}
bool isHappy(int n) {
int tim = 0;
while (tim < 100) {
n = plus(n);
tim ++;
if (n == 1) return true;
}
return n == 1;
}
};