Delete operation for two strings

String Dynamic Programming

65.3% acceptance

Jan 13, 2026

6142

Given two strings word1 and word2, return the minimum number of steps required to make word1 and word2 the same. In one step, you can delete exactly one character in either string.

Solution

Rust

Time O(n * m)

Space O(n * m)

LeetCode

solution.rs

impl Solution {
  pub fn min_distance(word1: String, word2: String) -> i32 {
    let w1: Vec<u8> = word1.bytes().collect();
    let w2: Vec<u8> = word2.bytes().collect();
    let (m, n) = (w1.len(), w2.len());
    let mut dp = vec![vec![0usize; n + 1]; m + 1];
    for i in 1..=m {
      for j in 1..=n {
        dp[i][j] = if w1[i-1] == w2[j-1] {
          dp[i-1][j-1] + 1
        } else {
          dp[i-1][j].max(dp[i][j-1])
        };
      }
    }
    let lcs = dp[m][n] as i32;
    (m as i32 - lcs) + (n as i32 - lcs)
  }
}