Print kth least significant bit of a number

Question

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Answer 1

Print k^th least significant bit of a number

To explain how to print the kth least significant bit of a number, we'll break down the process into several steps, including an explanation of what the least significant bit is, how to extract it, and provide example codes in different programming languages.

1. Understanding the Least Significant Bit (LSB)

The least significant bit (LSB) of a binary number is the rightmost bit, representing the smallest power of 2 in the binary representation of the number. It holds the least value in the binary number.

2. Extracting the kth Least Significant Bit

To extract the kth least significant bit of a number, we can use bitwise AND operation with a mask. The mask is constructed to isolate the kth bit.

3. Algorithm Steps

Here are the steps to extract the kth least significant bit:

1. Create a mask to isolate the kth bit. The mask can be generated by left-shifting 1 by k positions.
2. Perform a bitwise AND operation between the number and the mask.
3. Print the result of the bitwise AND operation.

Example Codes

Below are example codes demonstrating how to print the kth least significant bit of a number in different programming languages.

Python

def print_kth_lsb(number, k):
    # Create a mask to isolate the kth bit
    mask = 1 << k
    # Perform a bitwise AND operation
    result = number & mask
    # Print the result (0 or 1)
    print("The {}th least significant bit is: {}".format(k, result >> k))

# Example usage
number = 25
k = 3
print_kth_lsb(number, k)  # Output: The 3rd least significant bit is: 0
 

C++

#include <iostream>

int printKthLSB(int number, int k) {
    // Create a mask to isolate the kth bit
    int mask = 1 << k;
    // Perform a bitwise AND operation
    int result = number & mask;
    // Print the result (0 or 1)
    std::cout << "The " << k << "th least significant bit is: " << (result >> k) << std::endl;
    return result >> k;
}

int main() {
    int number = 25;
    int k = 3;
    printKthLSB(number, k);  // Output: The 3rd least significant bit is: 0
    return 0;
}
 

Explanation

• In both Python and C++, we first create a mask by left-shifting 1 by k positions to isolate the kth bit.
• Then, we perform a bitwise AND operation between the number and the mask to extract the kth bit.
• Finally, we print the result, which will be either 0 or 1, indicating the value of the kth least significant bit.

These example codes demonstrate a simple and efficient way to extract and print the kth least significant bit of a number in different programming languages.

Answer 2

FAQs on Print kth least significant bit of a number

Q: What is the least significant bit (LSB) of a number?

A: The least significant bit (LSB) of a number is the bit position that represents the smallest (lowest-order) place value in the binary representation of the number. It's the rightmost bit in the binary representation. For example, in the binary number 10110, the LSB is 0.

Q: How do you determine the kth least significant bit of a number?

A: To determine the kth least significant bit of a number, you can perform a bitwise AND operation between the number and 2k. If the result is non-zero, then the kth bit is set (i.e., 1); otherwise, it's not set (i.e., 0).

Q: Can you provide an example code to print the kth least significant bit of a number?

A: Certainly! Below is a Python example code snippet:

def print_kth_lsb(num, k):
    # Perform bitwise AND operation
    if num & (1 << k):
        print(f"The {k}th least significant bit of {num} is 1")
    else:
        print(f"The {k}th least significant bit of {num} is 0")

# Example usage
number = 25  # Binary representation: 11001
k_value = 3
print_kth_lsb(number, k_value)
 

Q: What is the complexity of this algorithm?

A: The complexity of this algorithm is O(1), as it only involves a few bitwise operations regardless of the size of the number.

Q: How can I modify this code to handle invalid values of k?

A: You can add a check to ensure that k is within the valid range (0 to the number of bits in the number minus 1). Here's a modified version of the function:

def print_kth_lsb(num, k):
    if k < 0 or k >= num.bit_length():
        print(f"Error: Invalid value of k for number {num}")
        return
    if num & (1 << k):
        print(f"The {k}th least significant bit of {num} is 1")
    else:
        print(f"The {k}th least significant bit of {num} is 0")

Important Interview Questions and Answers on Print kth least significant bit of a number

Q: What is the least significant bit of a number?

The least significant bit (LSB) of a binary number is the rightmost bit. It represents the smallest place value in the binary number system.

Q: How do you print the kth least significant bit of a number?

To print the kth least significant bit of a number, you can use bitwise AND operation. You can AND the number with 2k−1, where k is the position of the bit starting from 1.

Example Code in Python:

def print_kth_least_significant_bit(number, k):
    # Shifting 1 to the kth position
    mask = 1 << (k - 1)
    # Performing bitwise AND operation
    result = number & mask
    # If result is non-zero, then the kth bit is 1, else 0
    if result != 0:
        print(f"The {k}th least significant bit is 1")
    else:
        print(f"The {k}th least significant bit is 0")

# Example usage
number = 21  # Binary: 10101
k = 3
print_kth_least_significant_bit(number, k)  # Output: The 3rd least significant bit is 1
 

Q: What is the time complexity of the solution?

The time complexity of this solution is O(1) because it involves only bitwise operations, which execute in constant time regardless of the size of the input.

Q: How would you handle invalid input, such as when k is greater than the number of bits in the number?

You can add a check to ensure that k is within the valid range of 1 to the number of bits in the number. If k is invalid, you can print an error message or handle it based on the requirements of the problem.