Sum in a matrix

Array Sorting Heap (Priority Queue) Matrix Simulation

60.4% acceptance

Feb 25, 2026

404

You are given a 0-indexed 2D integer array nums. Initially, your score is 0. Perform the following operations until the matrix becomes empty: From each row in the matrix, select the largest number and remove it. In the case of a tie, it does not matter which number is chosen. Identify the highest number amongst all those removed in step 1. Add that number to your score. Return the final score.

Solution

Rust

Time O(n log n)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn matrix_sum(nums: Vec<Vec<i32>>) -> i32 {
    let mut nums = nums;
    for row in &mut nums {
      row.sort_unstable();
    }
    let cols = nums[0].len();
    let mut score = 0;
    for c in (0..cols).rev() {
      let max_val = nums.iter().map(|row| row[c]).max().unwrap_or(0);
      score += max_val;
    }
    score
  }
}