1337-the-k-weakest-rows-in-a-matrix.js

/**
 * 1337. The K Weakest Rows in a Matrix
 * https://leetcode.com/problems/the-k-weakest-rows-in-a-matrix/
 * Difficulty: Easy
 *
 * You are given an m x n binary matrix mat of 1's (representing soldiers) and 0's (representing
 * civilians). The soldiers are positioned in front of the civilians. That is, all the 1's will
 * appear to the left of all the 0's in each row.
 *
 * A row i is weaker than a row j if one of the following is true:
 * - The number of soldiers in row i is less than the number of soldiers in row j.
 * - Both rows have the same number of soldiers and i < j.
 *
 * Return the indices of the k weakest rows in the matrix ordered from weakest to strongest.
 */

/**
 * @param {number[][]} mat
 * @param {number} k
 * @return {number[]}
 */
var kWeakestRows = function(mat, k) {
  const soldierCounts = mat
    .map((row, index) => [row.reduce((sum, val) => sum + val, 0), index])
    .sort((a, b) => a[0] - b[0] || a[1] - b[1]);

  return soldierCounts.slice(0, k).map(pair => pair[1]);
};