EditDistance.java

import java.util.Scanner;

public class EditDistance {
    public static int editDistance(String s, String t) {
        int[][] dp = new int[s.length() + 1][t.length() + 1];
        for (int i = 0; i <= s.length(); i++) {
            for (int j = 0; j <= t.length(); j++) {
                if (i == 0) {
                    dp[i][j] = j;
                } else if (j == 0) {
                    dp[i][j] = i;
                } else {
                    if (i>=1 && j>=1 && s.charAt(i-1) == t.charAt(j-1)) {
                        dp[i][j] = dp[i - 1][j - 1];
                    } else {
                        dp[i][j] = Math.min(dp[i - 1][j - 1], Math.min(dp[i - 1][j], dp[i][j - 1])) + 1;
                    }
                }
            }
        }
        return dp[s.length()][t.length()];
    }

    public static void main(String args[]) {
        Scanner scan = new Scanner(System.in);

        String s = scan.next();
        String t = scan.next();

        System.out.println(editDistance(s, t));
    }

}