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
class Solution {
public:
bool isHappy(int n) {
unordered_map<int, int> mp;
mp.insert({n, 1});
for (;;) {
int sum = 0;
while(n > 0) {
int x = n % 10;
n /= 10;
sum += x*x;
}
//cout << "sum " << sum << endl;
if (sum == 1) return true;
if (mp.count(sum) > 0 ) return false;
mp.insert({sum,1});
n = sum;
//cout << n << endl;
}
return false;
}
};