Convert the array such that the GCD of the array becomes 1 in C++

In this tutorial, we will be discussing a program to convert the array such that the GCD of the array becomes one.

For this we will be provided with an array and a positive integer k. Our task is to convert the array elements such that the GCD of elements is 1 while only dividing the array elements by k any number of times until the element is less than k.

Example

 Live Demo

#include <bits/stdc++.h>
using namespace std;
//calculating the GCD of array
int calculate_gcd(int* arr, int n){
   int gcd = arr[0];
   for (int i = 1; i < n; i++)
      gcd = __gcd(arr[i], gcd);
   return gcd;
}
//checking if the operation is possible
bool convertGcd(int* arr, int n, int k){
   int gcd = calculate_gcd(arr, n);
   int max_prime = 1;
   for (int i = 2; i <= sqrt(gcd); i++) {
      while (gcd % i == 0) {
         gcd /= i;
         max_prime = max(max_prime, i);
      }
   }
   max_prime = max(max_prime, gcd);
   return (max_prime <= k);
}
int main(){
   int arr[] = { 10, 15, 30 };
   int k = 6;
   int n = sizeof(arr) / sizeof(arr[0]);
   if (convertGcd(arr, n, k) == true)
   cout << "Yes";
   else
      cout << "No";
   return 0;
}

Output

Yes