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Binary to Gray code using recursion
• Last Updated : 14 Apr, 2021

Given Binary code of a number as a decimal number, we need to convert this into its equivalent Gray Code
Examples :

```Input : 1001
Output : 1101

Input : 11
Output : 10```

In gray code, only one bit is changed in 2 consecutive numbers.

Algorithm :

```binary_to_grey(n)
if n == 0
grey = 0;
else if last two bits are opposite  to each other
grey = 1 + 10 * binary_to_gray(n/10))
else if last two bits are same
grey = 10 * binary_to_gray(n/10))```

Below is implementation of above approach :

## CPP

 `// CPP program to convert Binary to``// Gray code using recursion``#include ``using` `namespace` `std;` `// Function to change Binary to``// Gray using recursion``int` `binary_to_gray(``int` `n)``{``    ``if` `(!n)``        ``return` `0;` `    ``// Taking last digit``    ``int` `a = n % 10;``    ` `    ``// Taking second last digit``    ``int` `b = (n / 10) % 10;``        ` `    ``// If last digit are opposite bits``    ``if` `((a && !b) || (!a && b))        ``            ``return` `(1 + 10 * binary_to_gray(n / 10));``        ` `    ``// If last two bits are same``    ``return` `(10 * binary_to_gray(n / 10));``}` `// Driver Function``int` `main()``{``    ``int` `binary_number = 1011101;``    ` `    ``printf``(``"%d"``, binary_to_gray(binary_number));``    ``return` `0;``}`

## Java

 `// Java program to convert``// Binary code to Gray code``import` `static` `java.lang.StrictMath.pow;``import` `java.util.Scanner;` `class` `bin_gray``{``    ``// Function to change Binary to``    ``// Gray using recursion``    ``int` `binary_to_gray(``int` `n, ``int` `i)``    ``{``        ``int` `a, b;``        ``int` `result = ``0``;``        ``if` `(n != ``0``)``        ``{``            ``// Taking last digit``            ``a = n % ``10``;``            ` `            ``n = n / ``10``;``            ` `            ``// Taking second last digit``            ``b = n % ``10``;``        ` `            ``if` `((a & ~ b) == ``1` `|| (~ a & b) == ``1``)``            ``{``                ``result = (``int``) (result + pow(``10``,i));``            ``}``            ` `            ``return` `binary_to_gray(n, ++i) + result;``        ``}``        ``return` `0``;``    ``}` `    ``// Driver Function``    ``public` `static` `void` `main(String[] args)``    ``{``        ``int` `binary_number;``        ``int` `result = ``0``;``        ``binary_number = ``1011101``;``        ` `        ``bin_gray obj = ``new` `bin_gray();``        ``result = obj.binary_to_gray(binary_number,``0``);``        ` `        ``System.out.print(result);``    ``}``}` `// This article is contributed by Anshika Goyal.`

## Python3

 `# Python3 code to convert Binary``# to Gray code using recursion` `# Function to change Binary to Gray using recursion``def` `binary_to_gray( n ):``    ``if` `not``(n):``        ``return` `0``        ` `    ``# Taking last digit   ``    ``a ``=` `n ``%` `10``    ` `     ``# Taking second last digit``    ``b ``=` `int``(n ``/` `10``) ``%` `10``    ` `    ``# If last digit are opposite bits``    ``if` `(a ``and` `not``(b)) ``or` `(``not``(a) ``and` `b):``        ``return` `(``1` `+` `10` `*` `binary_to_gray(``int``(n ``/` `10``)))``    ` `    ``# If last two bits are same``    ``return` `(``10` `*` `binary_to_gray(``int``(n ``/` `10``)))` `# Driver Code``binary_number ``=` `1011101``print``( binary_to_gray(binary_number), end``=``'')` `# This code is contributed by "Sharad_Bhardwaj".`

## C#

 `// C# program to convert``// Binary code to Gray code``using` `System;` `class` `GFG {``    ` `    ``// Function to change Binary to``    ``// Gray using recursion``    ``static` `int` `binary_to_gray(``int` `n, ``int` `i)``    ``{``        ``int` `a, b;``        ``int` `result = 0;``        ``if` `(n != 0)``        ``{``            ` `            ``// Taking last digit``            ``a = n % 10;``            ` `            ``n = n / 10;``            ` `            ``// Taking second last digit``            ``b = n % 10;``        ` `            ``if` `((a & ~ b) == 1 || (~ a & b) == 1)``            ``{``                ``result = (``int``) (result + Math.Pow(10,i));``            ``}``            ` `            ``return` `binary_to_gray(n, ++i) + result;``        ``}``        ` `        ``return` `0;``    ``}` `    ``// Driver Function``    ``public` `static` `void` `Main()``    ``{``        ``int` `binary_number;``        ``binary_number = 1011101;``        ` `        ``Console.WriteLine(binary_to_gray(binary_number,0));``    ``}``}` `// This article is contributed by vt_m.`

## PHP

 ``

## Javascript

 ``

Output :

`1110011`

Assume that the binary number is in the range of integer. For larger value we can take binary number as string.

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