Greatest Common Divisor

Posted: 9 Dec, 2020
Difficulty: Easy


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You are given two numbers, ‘X’ and ‘Y’. Your task is to find the greatest common divisor of the given two numbers.

The Greatest Common Divisor of any two integers is the largest number that divides both integers.

For Example:
You are given ‘X’ as 20 and ‘Y’ as 15. The greatest common divisor, which divides both 15 and 20, is 5. Hence the answer is 5.
Input Format:
The first line of input contains ‘T’, representing the number of test cases. 

The first line of each test case contains two space-separated integers, ‘X’ and ‘Y’, representing the given numbers.
Output Format:
For each test case, print a single integer representing the Greatest Common Divisor of ‘X’ and ‘Y’.

Print a separate line for each test case.
You do not need to print anything, it has already been taken care of. Just implement the given function.
1 <= T <= 10
1 <= X, Y <= 10^9
Approach 1

In this approach, we know the minimum value of a common factor of two integers is 1, and the maximum value of a common factor is the minimum value of the given two integers. 

Therefore we will maintain a variable ans to store GCD. We set the initial value of ans as 1. We will iterate through the integers from 2 to the minimum of X and Y. We will check for each integer if X and Y are divisible by the integer, then update the ans with the integer. In the end, we return the variable ans.



  • Set the variable ans as 1. The variable ans stores the greatest common divisor of X and Y.
  • Iterate num from 2 to the minimum of X and Y.
    • If X and Y are divisible by num, set ans as num.
  • Finally, return the variable ans.
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