leetcode 202. Happy Number

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.

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

用map来存出现过的数

class Solution {
public:
bool isHappy(int n)
{
map<int,int> p;
while (n != 1 && p.find(n) == p.end())
{
int sum = 0;
p
++;
while (n != 0)
{
sum += pow(n % 10, 2);
n /= 10;
}
n = sum;
}
return n==1;
}
};