clueless coding // TODO: be smarter

LeetCode Delete Operation for Two Strings: Java Solution



Problem Statement


Given two words word1 and word2, find the minimum number of steps required to make word1 and word2 the same, where in each step you can delete one character in either string.

You can assume that the given words are below length 500, and that all letters are lowercase.

Function Signature (Java):
  int minDistance(String word1, String word2)

Inputs:
  word1 = "sea"
  word2 = "eat"

Outputs:
  2

Step 1: "sea" -> "ea"
Step 2: "eat" -> "ea"



TL;DR Code Solution


public int minDistance(String word1, String word2) {

    int len1 = word1.length(), len2 = word2.length();
    if (len1 == 0) return len2;
    if (len2 == 0) return len1;

    // dp[i][j] stands for distance of first i chars of word1 and first j chars of word2
    int[][] dp = new int[len1 + 1][len2 + 1];
    for (int i = 0; i <= len1; i++)
        dp[i][0] = i;
    for (int j = 0; j <= len2; j++)
        dp[0][j] = j;

    for (int i = 1; i <= len1; i++) {
        for (int j = 1; j <= len2; j++) {
            if (word1.charAt(i - 1) == word2.charAt(j - 1))
                dp[i][j] = dp[i - 1][j - 1];
            else
                dp[i][j] = Math.min(dp[i - 1][j] + 1, dp[i][j - 1] + 1);
        }
    }

    return dp[len1][len2];

}