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:
int getSquare(int num){ //because square operation is very often, so enum the result
switch(num){
case : return ;
case : return ;
case : return ;
case : return ;
case : return ;
case : return ;
case : return ;
case : return ;
case : return ;
case : return ;
}
}
bool isHappy(int n) {
if(n == ) return false;
set<int> squareSum;
return dfs(n, squareSum);
}
bool dfs(int n, set<int>& squareSum){
int tmp;
int sum = ;
while(n){
tmp = n%;
sum += getSquare(tmp);
n /= ;
}
if(sum == ) return true;
else if(squareSum.find(sum)!=squareSum.end()) return false;
else {
squareSum.insert(sum);
return dfs(sum, squareSum);
}
}
};