Set kth Bit

Problem

Given a number N and a value K. From the right, set the Kth bit in the binary representation of N. The position of Least Significant Bit(or last bit) is 0, the second last bit is 1 and so on.

Examples:

Example 1:

Input:
N = 10 
K = 2
Output:
14
Explanation:
Binary representation of the given number 10 is: 1 0 1 0, number of bits in the binary reprsentation is 4. Thus 2nd bit from right is 0. The number after changing this bit to 1 is: 14(1 1 1 0).

Example 2:

Input:
N = 15 
K = 3
Output:
15
Explanation:
The binary representation of the given number 15 is: 1 1 1 1, number of bits in the binary representation is 4. Thus 3rd bit from the right is 1. The number after changing this bit to 1 is 15(1 1 1 1).

Your task:

You don't need to read input or print anything. Your task is to complete the function setKthBit() which takes two integer N and K as input parameter and returns an integer after setting the K'th bit in N.

• Expected Time Complexity: $O(1)$
• Expected Auxiliary Space: $O(1)$

Constraints:

• $1<=N<=10^9$
• $0 <= K < X$, where X is the number of bits in the binary representation of N.

Solution

Python

def setKthBit(self, N, K):
	mask = 1 << K
    result = N | mask
    return result

Java

static int setKthBit(int N,int K){
    int mask = 1 << K;
    int result = N | mask;
    return result;
}

C++

int setKthBit(int N, int K) {
    int mask = 1 << K;
    int result = N | mask;
    return result;
}

C

int setKthBit(int N, int K) {
    int mask = 1 << K;
    int result = N | mask;
    return result;
}

• Time Complexity: $O(1)$
• Auxiliary Space: $O(1)$