LeetCode Challenges #3: Performing K-Or Operation on Array

Exploring ‘easy’ LeetCode problems: solutions, strategies, and insights. Dive into my journey with coding challenges!

Background

Embarking on yet another challenge in my journey through LeetCode, I encountered a fascinating problem involving the application of bitwise operations. The task at hand was to perform a K-or operation on an array of integers, a concept that piqued my interest and prompted me to delve deeper. Join me as I dissect this problem, outline my approach to solving it, and explore the insights gained along the way.

Problem: Performing K-Or Operation on Array

The question is like: You are given an integer array nums, and an integer k. Let’s introduce K-or operation by extending the standard bitwise OR. In K-or, a bit position in the result is set to 1 if at least k numbers in nums have a 1 in that position.Return the K-or of nums.

Understanding the Problem

The problem statement presents us with a variation of the bitwise OR operation called K-or. To tackle this problem effectively, we need to comprehend the K-or operation’s essence and how it differs from the standard OR operation. It’s crucial to devise a strategy that efficiently applies the K-or operation to the given array while maintaining clarity and correctness.

Solving the Problem

To address this problem, I opted for a straightforward yet efficient solution using PHP. Below is the step-by-step breakdown of my implementation:

class Solution {

    /**
     * @param Integer[] $nums
     * @param Integer $k
     * @return Integer
     */
    function findKOr($nums, $k) {
        $result = 0;
        $n = count($nums);
        
        for ($i = 0; $i < 32; $i++) {
            $count = 0;
            
            for ($j = 0; $j < $n; $j++) {
                if (($nums[$j] >> $i) & 1) {
                    $count++;
                }
            }
            
            if ($count >= $k) {
                $result |= (1 << $i);
            }
        }
        
        return $result;
    }
}

In this solution:

• We initialize the result variable to 0.
• We iterate through each bit position from right to left (assuming integers are 32-bit in PHP).
• For each bit position, we count the number of set bits in that position across all numbers in the array.
• If the count is greater than or equal to k, we set that bit in the result to 1 using the bitwise OR operation.
• Finally, we return the resulting number.

Approach Justification

The approach taken in the kOrOperation function involves iterating through each bit position of the integers in the array and counting the number of set bits (1s) at that position across all numbers. Let’s break down why this approach is chosen:

• Understanding the K-or operation: In the K-or operation, we need to determine whether to set a particular bit in the result to 1 based on whether at least k numbers in the array have a 1 in that position. To achieve this, we iterate through each bit position and count the number of set bits at that position.
• Iterating through bit positions: Since integers in PHP are typically 32-bit, we iterate through each bit position from right to left using the outer loop for ($i = 0; $i < 32; $i++). This ensures we cover all possible bit positions in the integers.
• Counting set bits: Within the outer loop, we have an inner loop that iterates through each number in the array. For each number, we shift its bits to the right by i positions and check if the least significant bit is set (& 1). If it is set, we increment the count.
• Determining whether to set the bit in the result: After counting the set bits at the current position, we compare the count with k. If the count is greater than or equal to k, it means that at least k numbers have a 1 in that position. In such cases, we set the corresponding bit in the result to 1 using the bitwise OR operation ($result |= (1 « $i)).
• Returning the result: Once we’ve iterated through all bit positions and set the bits in the result accordingly, we return the final result.

If you like to read further …

This problem provided an opportunity to explore bitwise operations and problem-solving strategies in PHP. By applying a straightforward approach and optimizing where possible, I effectively performed the K-or operation on the given array, meeting the requirements set forth by the problem statement.

Join me in tackling more LeetCode challenges and expanding our problem-solving skills!

Happy coding! 🚀