Lucky numbers in a matrix

Array Matrix

80.0% acceptance

Feb 25, 2026

2338

123

Given an m x n matrix of distinct numbers, return all lucky numbers in the matrix in any order. A lucky number is an element of the matrix such that it is the minimum element in its row and maximum in its column.

Solution

Rust

Time O(n²)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn lucky_numbers(matrix: Vec<Vec<i32>>) -> Vec<i32> {
    let m = matrix.len();
    let n = matrix[0].len();
    let row_min: Vec<i32> = matrix.iter().map(|row| *row.iter().min().unwrap()).collect();
    let col_max: Vec<i32> = (0..n).map(|c| (0..m).map(|r| matrix[r][c]).max().unwrap()).collect();
    let mut result = vec![];
    for r in 0..m {
      for c in 0..n {
        if matrix[r][c] == row_min[r] && matrix[r][c] == col_max[c] {
          result.push(matrix[r][c]);
        }
      }
    }
    result
  }
}