Work Space And I

  There are two recursive call for the GCD (Greatest Common Divisor) and HCF highest common factor. using both we solve the problem.

 

  #include <bits/stdc++.h> using namespace std ; /* this program is for finding the prime number till the given number */ void primeSieve ( long long n ) {     long long prime [ n + 1 ] = { 0 };     for ( long long i = 2 ; i <= n ; i ++ )     {         if ( prime [ i ] == 0 )         for ( long long j = i * i ; j <= n ; j += i )         {             prime [ j ] = 1 ;         }             }     for ( long long i = 2 ; i <= n ; i ++ )     {         if ( prime [ i ] == 0 )         cout << i << " " ;     }         } int main () {     long long n ;     cin >> n ;     primeSieve ( n );     return 0 ; }

#include <bits/stdc++.h> using namespace std ; // this is the program to find the number of 1's bit in a number int count1nsBit ( int n ) {     int count = 0 ;     while ( n )     {         n = n & n - 1 ;         count ++ ;     }     return count ; } int main () {     int n ;     cin >> n ;     cout << count1nsBit ( n );     return 0 ; } /* input an output tast are comments */

// To check the number is power if two or not bool ispowOf2two(int n) {  return (n&&!(n&n-1)); } int main () {  cout<< ispowOf2two(16);  return 0; }