Grokking Data Structures & Algorithms for Coding Interviews
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Solution: Row With Maximum Ones(easy)

Problem Statement

Given a binary matrix that has dimensions m * n, consisting of ones and zeros. Determine the row that contains the highest number of ones and return two values: the zero-based index of this row and the actual count of ones it possesses.

If there is a tie, i.e., multiple rows contain the same maximum number of ones, we must select the row with the lowest index.

Examples

Example 1:

  • Input: [[1, 0], [1, 1], [0, 1]]
  • Expected Output: [1, 2]
  • Justification: The second row [1, 1] contains the most ones, so the output is [1, 2].

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L

luidymorais

· 3 years ago

Despite the solution explanation tells maxOnexIdx variable will initialize with -1, the code is showing is starting with zero. What is expected behaviour if there is no Ones in 2D-matrix?

Show 1 reply
Tal Ya'akov

Tal Ya'akov

· 18 days ago

class Solution {
    findMaxOnesRow(mat) {
        let maxOnesIdx = 0;
        let maxOnesCount = 0;
        const reduced = mat.map(row => row.reduce(
            (sum, x) => sum + x
        ), 0);

        for (let m = reduced.length - 1; m > -1; m--) {
            const curr = reduced[m];
            if (curr >= maxOnesCount) {
                maxOnesCount = curr;
                maxOnesIdx = m;
            }
        }
        return [maxOnesIdx, maxOnesCount];
    }
}