How do you solve Minimum Bitwise OR From Grid on LeetCode?

Minimum Bitwise OR From Grid (LeetCode #3858) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(m * n) time complexity and O(1) space complexity. Key insight: Greedily check each bit from highest to lowest.

What is the time complexity of Minimum Bitwise OR From Grid?

The optimal solution for Minimum Bitwise OR From Grid runs in O(m * n) time and uses O(1) space. The complexity comes from checking each bit across all rows, leading to linear complexity relative to the number of elements.

What is the brute force solution for Minimum Bitwise OR From Grid?

The brute force approach for Minimum Bitwise OR From Grid is Brute Force, with O(n²) time complexity and O(1) space complexity. Select every possible combination of numbers from each row and compute the bitwise OR. This method guarantees finding the minimum but is inefficient. The optimal Optimal Solution approach improves this to O(m * n).

What algorithm or data structure is used to solve Minimum Bitwise OR From Grid?

Minimum Bitwise OR From Grid uses the following concepts: Array, Greedy, Bit Manipulation, Matrix. The recommended patterns to study are: Bit Manipulation, Greedy Algorithms.

What are the interview tips for Minimum Bitwise OR From Grid?

Explain your thought process clearly. Use examples to illustrate your approach. Practice similar bit manipulation problems.

What are common mistakes when solving Minimum Bitwise OR From Grid?

Forgetting to check all rows for each bit. Incorrectly updating the result when a bit can be excluded.

#3858

Minimum Bitwise OR From Grid

Medium

ArrayGreedyBit ManipulationMatrixBit ManipulationGreedy Algorithms

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(m * n)
Space	O(1)	O(1)

💡

Intuition

Time O(m * n)Space O(1)

Use a greedy approach by checking each bit from the most significant to the least significant. If a bit can be excluded from the OR by selecting numbers with that bit unset in all rows, we skip it.

⚙️

Algorithm

3 steps

1Step 1: Initialize result as 0.
2Step 2: For each bit position from highest to lowest, check if we can keep the bit unset by selecting numbers from each row that do not have this bit set.
3Step 3: If possible, update the result to include this bit.

solution.py7 lines

1def min_bitwise_or(grid):
2    result = 0
3    for bit in range(20, -1, -1):
4        temp = result | (1 << bit)
5        if all(any((num & temp) == 0 for num in row) for row in grid):
6            result = temp
7    return result

ℹ

Complexity note: The complexity comes from checking each bit across all rows, leading to linear complexity relative to the number of elements.

1Greedily check each bit from highest to lowest.
2Use bitwise operations to determine possible selections.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.