题解 | #快乐数#

class Solution 
{
public://双指针
int happy(int x)
{
    int sum=0;
    int m=0;
    while(x)
    {
        m=x%10;
        sum+=m*m;
        x=x/10;
    }
    return sum;
}
    bool happynum(int n) 
    {
        //定义快慢双指针
        //快指针一次走两步，慢指针一次走一步
        int slow=n,fast=happy(n);
        while(slow!=fast)
        {
            slow=happy(slow);
            fast=happy(happy(fast));
        }
        return slow==1;//判断solw是否等于1，等于为真,返回true
    }
};