(Leet Code c++)Happy Number

202. Happy Number

 

Write an algorithm to determine if a number n 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.
• 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.

Return true if n is a happy number, and false if not.

 

Example 1:

Input: n = 19 Output: true Explanation: 12 + 92 = 82 82 + 22 = 68 62 + 82 = 100 12 + 02 + 02 = 1

Example 2:

Input: n = 2 Output: false

 

Constraints:

• 1 <= n <= 231 - 1

 

class Solution {
public:
    bool isHappy(int n) {
        map<int, bool> m;
        
        while(n){
            int num = 0;
            
            while(n){
                num += pow(n % 10, 2);
                n /= 10;
            }
            
            if(num == 1){
                return true;
            }
            else{
                if(!m[num]){
                    m[num] = true;
                    n = num;
                }
                else{
                    return false;
                }
            }
        }
        
        return true;
    }
};