leetcode 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

Credits:

Special thanks to @mithmatt and @ts for
adding this problem and creating all test cases.

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class Solution {
public:
bool isHappy(int n) {
if(n==1) return true;
map<int, int> exits;

int cnt = 1, sum = 0;

while(exits.count(n)==0) {
exits
= 1;
if(n==1) return true;

while(n > 0) {
sum += (n%10)*(n%10);
n = n / 10;
}

n = sum;
sum = 0;
}

return false;
}
}