[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
Solution: 
Idea: For happy numbers, the number will equal 1 at some point. For others, the numbers will show in cycles. For instance, 

<span style="font-size:14px;">class Solution {
public:
bool isHappy(int n) {
unordered_map<int,int> hs;
bool ish = false;
while(1){
n = digit_square_sum(n);
if (n==1){
ish = true;
break;
}
else{
hs
++;
if(hs
>1){
ish = false;
break;
}
}
}
return ish;
}
int digit_square_sum(int n){
int sum = 0;
while(n){
sum += pow(n%10,2);
n = n/10;
}
return sum;

}
};</span>