LeetCode 2397: Maximum Rows Covered by Columns Solution

Master LeetCode problem 2397 (Maximum Rows Covered by Columns), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

2397. Maximum Rows Covered by Columns

Medium

Array Backtracking Bit Manipulation Matrix Enumeration

Problem Explanation

Explanation:

To solve this problem, we can iterate over all possible combinations of selecting numSelect columns from the given matrix. For each combination, we check how many rows can be covered using those columns. We keep track of the maximum number of rows covered and return that as the result.

Generate all combinations of selecting numSelect columns.
For each combination, check how many rows can be covered.
Return the maximum number of rows covered.

Time Complexity:

Generating all combinations: O(2^n)
Checking rows covered for each combination: O(m)
Total time complexity: O(2^n * m)

Space Complexity:
The space complexity is O(1) as we are not using any additional data structures that grow with the input size.

Solution Code

class Solution {
    public int maxRowsCovered(int[][] matrix, int numSelect) {
        int m = matrix.length;
        int n = matrix[0].length;
        int maxCovered = 0;

        for (int comb = 0; comb < (1 << n); comb++) {
            if (Integer.bitCount(comb) != numSelect) continue;
            int rowsCovered = 0;

            for (int row = 0; row < m; row++) {
                boolean covered = true;
                for (int col = 0; col < n; col++) {
                    if ((comb & (1 << col)) > 0 && matrix[row][col] == 1) {
                        covered = true;
                        break;
                    }
                }
                if (covered) rowsCovered++;
            }

            maxCovered = Math.max(maxCovered, rowsCovered);
        }

        return maxCovered;
    }
}

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