# Find a value whose XOR with given number is maximum

Given a value X, the task is to find the number Y which will give maximum value possible when XOR with X.
(Assume X to be 8 bits) Maximum possible value of X and Y both is 255.

Examples:

```Input:  X = 2
Output: 253
Binary Representation of X = 00000010
Binary Representation of Y = 11111101
Maximum XOR value: 11111111

Input:  X = 200
Output: 55

```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach: In order to ensure maximum value of XOR, we need to set all those bits ON which are OFF in X. So for that, Y should have all bits ON which are OFF in X and OFF which are ON in X as (0^1 = 1 and 1^0 = 1). So Y should be the 1’s complement representation of X.

Below is the implementation of the above approach:

## C++

 `// C++ implementation of the above approach ` `#include ` `using` `namespace` `std; ` ` `  `// Function To Calculate Answer ` `int` `calculate(``int` `X) ` `{ ` `    ``// Find number of bits in the given integer ` `    ``int` `number_of_bits = 8; ` ` `  `    ``// XOR the given integer with poe(2, ` `    ``// number_of_bits-1 and print the result ` `    ``return` `((1 << number_of_bits) - 1) ^ X; ` `} ` ` `  `// Driver Code ` `int` `main() ` `{ ` `    ``int` `X = 4; ` ` `  `    ``cout << ``"Required Number is : "` `         ``<< calculate(X) << endl; ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java implementation of the above approach ` ` `  `import` `java.io.*; ` ` `  `class` `GFG { ` `     `  `// Function To Calculate Answer ` `static` `int` `calculate(``int` `X) ` `{ ` `    ``// Find number of bits in the given integer ` `    ``int` `number_of_bits = ``8``; ` ` `  `    ``// XOR the given integer with poe(2, ` `    ``// number_of_bits-1 and print the result ` `    ``return` `((``1` `<< number_of_bits) - ``1``) ^ X; ` `} ` ` `  `// Driver Code ` ` `  ` `  `    ``public` `static` `void` `main (String[] args) { ` `        ``int` `X = ``4``; ` ` `  `    ``System.out.println( ``"Required Number is : "` `        ``+calculate(X)); ` `    ``} ` `} ` `// This code is contributed by shs.. `

## Python3

 `# Python3 implementation of the above approach  ` ` `  `# Function To Calculate Answer  ` `def` `calculate(X):  ` `  `  `    ``# Find number of bits in the given integer  ` `    ``number_of_bits ``=` `8`  `   `  `    ``# XOR the given integer with poe(2,  ` `    ``# number_of_bits-1 and print the result  ` `    ``return` `((``1` `<< number_of_bits) ``-` `1``) ^ X  ` `   `  `# Driver Code  ` `if` `__name__ ``=``=` `"__main__"``: ` `  `  `    ``X ``=` `4`  `    ``print``(``"Required Number is:"``, calculate(X))  ` `   `  `# This code is contributed by Rituraj Jain `

## C#

 `// C# implementation of the above approach ` `using` `System; ` ` `  `class` `GFG ` `{ ` `     `  `// Function To Calculate Answer ` `static` `int` `calculate(``int` `X) ` `{ ` `    ``// Find number of bits in ` `    ``// the given integer ` `    ``int` `number_of_bits = 8; ` ` `  `    ``// XOR the given integer with poe(2, ` `    ``// number_of_bits-1 and print the result ` `    ``return` `((1 << number_of_bits) - 1) ^ X; ` `} ` ` `  `// Driver Code ` `public` `static` `void` `Main ()  ` `{ ` `    ``int` `X = 4; ` ` `  `    ``Console.WriteLine(``"Required Number is : "` `+  ` `                                 ``calculate(X)); ` `} ` `} ` ` `  `// This code is contributed by shs.. `

## PHP

 ` `

Output:

```Required Number is : 251
```

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