Leetcode no. 72

72. Edit Distance

Given two words word1 and word2, find the minimum number of steps required to convert word1 to word2. (each operation is counted as 1 step.)

You have the following 3 operations permitted on a word:

a) Insert a character
b) Delete a character
c) Replace a character

public class Solution {
    public int minDistance(String word1, String word2) {
        if (word1.length()==0) return word2.length();
        if (word2.length()==0) return word1.length();
        int[][] dp= new int[word1.length()+1][word2.length()+1];
        for (int i = 0; i <= word1.length(); i++) {
            dp[i][0]= i;
        }
        for (int j = 0; j <= word2.length(); j++) {
            dp[0][j]= j;
        }
        for (int i = 1; i <= word1.length(); i++) {
            for (int j = 1; j <= word2.length(); j++) {
                if (word1.charAt(i-1)== word2.charAt(j-1))
                    dp[i][j]= dp[i-1][j-1];
                else dp[i][j]= Math.min(Math.min(dp[i][j-1], dp[i-1][j]), dp[i-1][j-1]) +1;
            }
        }
        return dp[word1.length()][word2.length()];
    }
}