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Algorithm to Find the HCF (Highest Common Factor) of Two Numbers

Input: Two numbers, a and b.
Initialize: hcf to 1.
Loop: From i = 1 to the minimum of a and b:

If both a and b are divisible by i, set hcf to i.

Output: The value of hcf.

C Program to Find the HCF of Two Numbers

#include <stdio.h>

// Function to find the HCF of two numbers
int findHCF(int a, int b) {
    int hcf = 1; // Initialize HCF to 1

    // Find the minimum of a and b
    int min = (a < b) ? a : b;

    // Loop from 1 to the minimum of a and b
    for (int i = 1; i <= min; i++) {
        // If both a and b are divisible by i, update hcf
        if (a % i == 0 && b % i == 0) {
            hcf = i;
        }
    }

    return hcf; // Return the HCF
}

int main() {
    int num1, num2;

    // Input two numbers from the user
    printf("Enter two numbers: ");
    scanf("%d %d", &num1, &num2);

    // Call the function to find the HCF
    int hcf = findHCF(num1, num2);

    // Print the HCF
    printf("The HCF of %d and %d is: %d\n", num1, num2, hcf);

    return 0;
}

Explanation:

Function Definition (findHCF):

This function takes two integers a and b as input.
It initializes hcf to 1, which will store the highest common factor.
The variable min is set to the minimum of a and b to limit the loop.
The for loop iterates from 1 to min. For each i, it checks if both a and b are divisible by i. If so, it updates hcf to i.
Finally, the function returns the value of hcf.

Main Function (main):

The main function prompts the user to enter two numbers.
It reads the input numbers using scanf.
It then calls the findHCF function to compute the HCF of the two numbers.
Finally, it prints the HCF.

This program uses a simple iterative method to find the HCF by checking all numbers from 1 to the minimum of the two given numbers.