快乐数--双指针

一：题目

题目链接：. - 力扣（LeetCode）

二：算法原理

三：代码编写

int Sum(int n){int sum = 0;while(n){sum += pow(n%10,2);n /= 10;}return sum;}bool isHappy(int n) {int slow = n,fast = Sum(n);while(slow != fast){slow = Sum(slow);fast = Sum(Sum(fast));}    return slow == 1;}