# Program to find GCD or HCF of two numbers using Middle School Procedure in C++

C++Server Side ProgrammingProgramming

In this tutorial, we will be discussing a program to find GCD or HCF of two numbers using Middle School Procedure.

For this we will be provided with two numbers. Our task is to find the GCD (greatest common divisor) or HCF (highest common factor) for the given values.

## Example

Live Demo

#include <bits/stdc++.h>
#define MAXFACTORS 1024
using namespace std;
//structure to store factorization
typedef struct{
int size;
int factor[MAXFACTORS + 1];
int exponent[MAXFACTORS + 1];
} FACTORIZATION;
void FindFactorization(int x, FACTORIZATION* factorization){
int i, j = 1;
int n = x, c = 0;
int k = 1;
factorization->factor[0] = 1;
factorization->exponent[0] = 1;
for (i = 2; i <= n; i++) {
c = 0;
while (n % i == 0) {
c++;
n = n / i;
}
if (c > 0) {
factorization->exponent[k] = c;
factorization->factor[k] = i;
k++;
}
}
factorization->size = k - 1;
}
//printing the factors
void DisplayFactorization(int x, FACTORIZATION factorization){
int i;
cout << "Prime factor of << x << = ";
for (i = 0; i <= factorization.size; i++) {
cout << factorization.factor[i];
if (factorization.exponent[i] > 1)
cout << "^" << factorization.exponent[i];
if (i < factorization.size)
cout << "*";
else
cout << "\n";
}
}
//gcd using Middle School procedure
int gcdMiddleSchoolProcedure(int m, int n){
FACTORIZATION mFactorization, nFactorization;
int r, mi, ni, i, k, x = 1, j;
FindFactorization(m, &mFactorization);
DisplayFactorization(m, mFactorization);
FindFactorization(n, &nFactorization);
DisplayFactorization(n, nFactorization);
int min;
i = 1;
j = 1;
while (i <= mFactorization.size && j <= nFactorization.size) {
if (mFactorization.factor[i] < nFactorization.factor[j])
i++;
else if (nFactorization.factor[j] < mFactorization.factor[i])
j++;
else{
min = mFactorization.exponent[i] > nFactorization.exponent[j] ? nFactorization.exponent[j] : mFactorization.exponent[i];
x = x * mFactorization.factor[i] * min;
i++;
j++;
}
}
return x;
}
int main(){
int m = 10, n = 15;
cout << "GCD(" << m << ", " << n << ") = " << gcdMiddleSchoolProcedure(m, n);
return (0);
}

## Output

GCD(10, 15) = Prime factor of << x << = 1*2*5
Prime factor of << x << = 1*3*5
5
Updated on 09-Sep-2020 11:40:38