happy.cpp

#include <iostream>
using namespace std;

class Solution {
public:
    /*int getNext(int n) {
        int sum = 0;
        while (n > 0) {
            int digit = n % 10;
            sum += digit * digit;
            n /= 10;
        }
        return sum;
    }

    bool isHappy(int n) {
        int seen[1000]; // Array to store seen numbers
        int index = 0;

        while (n != 1) {
            for (int i = 0; i < index; i++) {
                if (seen[i] == n) return false; // Cycle detected
            }
            seen[index++] = n;
            n = getNext(n);
        }
        return true;
    }*/
 /*   bool isHappy(int n) {
        int slow = n, fast = getNext(n);

        while (fast != 1 && slow != fast) {
            slow = getNext(slow);
            fast = getNext(getNext(fast));
        }
        return fast == 1;
    }*/
    
    int getnext(int n){
      int d,sum=0;
      while(n>0){
        d=n%10;
        n=n/10;
        sum+=d*d;
      } 
    return sum;
    }
    
    bool isHappy(int n){
      int slow=n,fast=getnext(n);
      while (fast != 1 && slow!=fast){
         slow=getnext(slow);
         fast=getnext(getnext(fast));
      }
      return fast==1;
    }  
};

int main() {
    int n;
    cin >> n;
    
    Solution obj;
    if (obj.isHappy(n))
        cout << "True\n";
    else
        cout << "False\n";

    return 0;
}