Greatest Common Divisor

Problem #26

Tags: arithmetic modulo classical if-else

Who solved this?

Also available in: Russian

It looks like none of beginner's courses on programming avoids practicing Euclid's algorithm for calculation of the greatest common divisor of two numbers.

Greatest Common Divisor or GCD of a and b is such an integer value c that both of a, b are divisible by it (e.g. leave no remainder) - and also c is the largest possible. For example gcd(20, 35) = 5 and gcd(13, 28) = 1. Euclid's algorithm is quite simple - we keep on subtracting smaller value (of a and b) from larger - and repeat this operation until values become equal - this last value will be gcd. For speeding up the process we can use modulo operation instead of subtraction.

For example:

20      35      - subtract first from second
20      15      - subtract second from first
5       15      - now subtract first from second twice
5       5       - and here is GCD

Least Common Multiple (or LCM) of a and b is such an integer d that it is divisible by both of them (and is the smallest of all possible). It can be found with the following rule:

lcm(a, b) = a * b / gcd(a, b)

The task

Input data contain number of test-cases in the first line.
Then lines with test-cases follow, each containing two numbers - for A and B.
Answer should contain GCD and LCM for each pair, surrounded by brackets and separated by spaces, for example:

input data:
2 3
4 10

(1 6) (2 20)
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