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Find the final X and Y when they are Altering under given condition
• Last Updated : 19 Apr, 2021

Given initial values of two positive integers X and Y, Find the final value of X and Y according to below alterations:

1. If X=0 or Y=0, terminate the process. Else, go to step 2;
2. If X >= 2*Y, then change the value of X to X – 2*Y, and repeat step 1. Else, go to step 3;
3. If Y >= 2*X, then assign the value of Y to Y – 2*X, and repeat step 1. Else, end the process.
Constraints: 1<=X, Y<=10^18

Examples:

```Input: X=12, Y=5
Output: X=0, Y=1
Explanation:
Initially X = 12, Y = 5
--> X = 2, Y = 5 (as X = X-2*Y)
--> X = 2, Y = 1 (as Y = Y-2*X)
--> X = 0, Y = 1 (as X = X-2*Y)
--> Stop         (as X = 0)

Input: X=31, Y=12
Output: X=7, Y=12
Explanation:
Initially X = 31, Y = 12
--> X = 7, Y = 12 (as X = X-2*Y)
--> Stop          (as (Y - 2*X) < 0)```

Approach: Since the initial values of X and Y can be as high as 10^18. Simple brute force approach will not work.
If we observe carefully, the problem statement is nothing but a sort of Euclid Algorithm, where we will replace all subtractions with modulo.
Implementation:

## C++

 `// CPP tp implement above approach` `#include ``using` `namespace` `std;` `// Function to get final value of X and Y``void` `alter(``long` `long` `int` `x, ``long` `long` `int` `y)``{``    ``// Following the sequence``    ``// but by replacing minus with modulo``    ``while` `(``true``) {` `        ``// Step 1``        ``if` `(x == 0 || y == 0)``            ``break``;` `        ``// Step 2``        ``if` `(x >= 2 * y)``            ``x = x % (2 * y);` `        ``// Step 3``        ``else` `if` `(y >= 2 * x)``            ``y = y % (2 * x);` `        ``// Otherwise terminate``        ``else``            ``break``;``    ``}` `    ``cout << ``"X="` `<< x << ``", "``         ``<< ``"Y="` `<< y;``}` `// Driver function``int` `main()``{` `    ``// Get the initial X and Y values``    ``long` `long` `int` `x = 12, y = 5;` `    ``// Find the result``    ``alter(x, y);` `    ``return` `0;``}`

## Java

 `// Java tp implement above approach``import` `java.io.*;` `class` `GFG``{``    ` `// Function to get final value of X and Y``static` `void` `alter(``long` `x, ``long` `y)``{``    ``// Following the sequence but by``    ``// replacing minus with modulo``    ``while` `(``true``)``    ``{` `        ``// Step 1``        ``if` `(x == ``0` `|| y == ``0``)``            ``break``;` `        ``// Step 2``        ``if` `(x >= ``2` `* y)``            ``x = x % (``2` `* y);` `        ``// Step 3``        ``else` `if` `(y >= ``2` `* x)``            ``y = y % (``2` `* x);` `        ``// Otherwise terminate``        ``else``            ``break``;``    ``}` `    ``System.out.println(``"X = "` `+ x + ``", "` `+``                       ``"Y = "` `+ y);``}` `// Driver Code``public` `static` `void` `main (String[] args)``{``    ``// Get the initial X and Y values``    ``long` `x = ``12``, y = ``5``;``    ` `    ``// Find the result``    ``alter(x, y);``}``}` `// This code is contributed by``// shk`

## Python3

 `# Python3 tp implement above approach``import` `math as mt` `# Function to get final value of X and Y``def` `alter(x, y):` `    ``# Following the sequence but by``    ``# replacing minus with modulo``    ``while` `(``True``):` `        ``# Step 1``        ``if` `(x ``=``=` `0` `or` `y ``=``=` `0``):``            ``break` `        ``# Step 2``        ``if` `(x >``=` `2` `*` `y):``            ``x ``=` `x ``%` `(``2` `*` `y)` `        ``# Step 3``        ``elif` `(y >``=` `2` `*` `x):``            ``y ``=` `y ``%` `(``2` `*` `x)` `        ``# Otherwise terminate``        ``else``:``            ``break``    ` `    ``print``(``"X ="``, x, ``", "``, ``"Y ="``, y)`  `# Driver Code` `# Get the initial X and Y values``x, y ``=` `12``, ``5` `# Find the result``alter(x, y)` `# This code is contributed by``# Mohit kumar 29`

## C#

 `// C# implementation of the approach``using` `System;` `class` `GFG``{` `    ``// Function to get final value of X and Y``    ``static` `void` `alter(``long` `x, ``long` `y)``    ``{``    ``// Following the sequence but by``    ``// replacing minus with modulo``    ``while` `(``true``)``    ``{``    ` `        ``// Step 1``        ``if` `(x == 0 || y == 0)``            ``break``;``        ` `        ``// Step 2``        ``if` `(x >= 2 * y)``            ``x = x % (2 * y);``        ` `        ``// Step 3``        ``else` `if` `(y >= 2 * x)``            ``y = y % (2 * x);``        ` `        ``// Otherwise terminate``        ``else``            ``break``;``        ``}``    ` `        ``Console.WriteLine(``"X = "` `+ x + ``", "` `+ ``"Y = "` `+ y);``    ``}``    ` `    ``// Driver Code``    ``public` `static` `void` `Main ()``    ``{``        ``// Get the initial X and Y values``        ``long` `x = 12, y = 5;``        ` `        ``// Find the result``        ``alter(x, y);``    ``}``}` `// This code is contributed by aishwarya.27`

## PHP

 `= 2 * ``\$y``)``            ``\$x` `= ``\$x` `% (2 * ``\$y``);` `        ``// Step 3``        ``else` `if` `(``\$y` `>= 2 * ``\$x``)``            ``\$y` `= ``\$y` `% (2 * ``\$x``);` `        ``// Otherwise terminate``        ``else``            ``break``;``    ``}` `    ``echo` `"X = "``, ``\$x``, ``", "``, ``"Y = "``, ``\$y``;``}` `// Driver Code` `// Get the initial X and Y values``\$x` `= 12 ;``\$y` `= 5 ;` `// Find the result``alter(``\$x``, ``\$y``);` `// This code is contributed by Ryuga``?>`

## Javascript

 ``
Output:
`X=0, Y=1`

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