Delete columns to make sorted

Array String

78.1% acceptance

Feb 25, 2026

2057

3014

You are given an array of n strings strs, all of the same length. The strings can be arranged such that there is one on each line, making a grid. For example, strs = ["abc", "bce", "cae"] can be arranged as follows: abc bce cae You want to delete the columns that are not sorted lexicographically. In the above example (0-indexed), columns 0 ('a', 'b', 'c') and 2 ('c', 'e', 'e') are sorted, while column 1 ('b', 'c', 'a') is not, so you would delete column 1. Return the number of columns that you will delete.

Solution

Rust

Time O(n²)

Space O(1)

LeetCode

solution.rs

impl Solution {
  pub fn min_deletion_size(strs: Vec<String>) -> i32 {
    let cols = strs[0].len();
    let rows = strs.len();
    let strs: Vec<Vec<u8>> = strs.iter().map(|s| s.bytes().collect()).collect();
    let mut count = 0;
    for c in 0..cols {
      for r in 1..rows {
        if strs[r][c] < strs[r-1][c] {
          count += 1;
          break;
        }
      }
    }
    count
  }
}