# Maximum Bitwise AND pair (X, Y) from given range such that X and Y can be same

Given a range [L, R], the task is to find a pair (X, Y), not necessarily distinct. Find the maximum possible value of the bitwise AND of the chosen integers.

Examples:

Input: L = 3, R = 7
Output: 7
Explanation:
In all the possible pairs, pair (7, 7) gives the maximum value for bitwise AND.

Input: L = 54, R = 55
Output: 55
Explanation:
In all the possible pairs, pair (55, 55) gives the maximum value for bitwise AND.

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

Naive Approach: To solve the problem mentioned above the naive method is to iterate from L to R and check the bitwise AND for every possible pair and print the maximum value in the end.

Time Complexity: O(N2)

Efficient Approach:

To optimize the above method we have to observe that here we have to integers L and R and we have to select two integers from the interval [L, R] so that their bitwise AND should be maximum. Bitwise AND of any two numbers between L and R will be always less than or equal to R only. So if we have to select two integers from the interval, we can choose the integers to be R and that’s the only way to maximize the bitwise AND.

Below is the implementation of above approach:

## C

 `// C implementation to find the ` `// Maximum Bitwise AND pair (X, Y) ` `// from given range such that ` `// X and Y can be same ` ` `  `#include ` ` `  `// Function to return the ` `// maximum bitwise AND ` `int` `maximumAND(``int` `L, ``int` `R) ` `{ ` `    ``return` `R; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `l = 3; ` `    ``int` `r = 7; ` ` `  `    ``printf``(``"%d"``, maximumAND(l, r)); ` ` `  `    ``return` `0; ` `} `

## C++

 `// C++ implementation to find the ` `// Maximum Bitwise AND pair (X, Y) ` `// from given range such that ` `// X and Y can be same ` ` `  `#include ` `using` `namespace` `std; ` ` `  `// Function to return the ` `// maximum bitwise AND ` `int` `maximumAND(``int` `L, ``int` `R) ` `{ ` `    ``return` `R; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `l = 3; ` `    ``int` `r = 7; ` ` `  `    ``cout << maximumAND(l, r); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java implementation to find the ` `// Maximum Bitwise AND pair (X, Y) ` `// from given range such that ` `// X and Y can be same ` ` `  `class` `GFG { ` ` `  `    ``// Function to return the ` `    ``// maximum bitwise AND ` `    ``static` `int` `maximumAND(``int` `L, ``int` `R) ` `    ``{ ` `        ``return` `R; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``int` `l = ``3``; ` `        ``int` `r = ``7``; ` `        ``System.out.print(maximumAND(l, r)); ` `    ``} ` `} `

## Python3

 `# Python3 implementation to find the  ` `# Maximum Bitwise AND pair (X, Y) ` `# from given range such that ` `# X and Y can be same ` ` `  `# Function to return the ` `# maximum bitwise AND  ` `def` `maximumAND(L, R): ` `    ``return` `R ` ` `  `# Driver code  ` `if` `__name__ ``=``=` `'__main__'``:  ` `    ``l ``=` `3` `    ``r ``=` `7` `    ``print``(maximumAND(l, r))  `

## C#

 `// C# implementation to find the ` `// maximum Bitwise AND pair (X, Y) ` `// from given range such that ` `// X and Y can be same ` `using` `System; ` ` `  `class` `GFG{ ` ` `  `// Function to return the ` `// maximum bitwise AND ` `static` `int` `maximumAND(``int` `L, ``int` `R) ` `{ ` `    ``return` `R; ` `} ` ` `  `// Driver code ` `public` `static` `void` `Main(String[] args) ` `{ ` `    ``int` `l = 3; ` `    ``int` `r = 7; ` `     `  `    ``Console.Write(maximumAND(l, r)); ` `} ` `} ` ` `  `// This code is contributed by amal kumar choubey `

Output:

```7
```

Time Complexity: O(1)

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Improved By : Amal Kumar Choubey