package DynamicProgramming;

/**
 * @author Kshitij VERMA (github.com/kv19971) LEVENSHTEIN DISTANCE dyamic programming implementation
 * to show the difference between two strings
 * (https://en.wikipedia.org/wiki/Levenshtein_distance)
 */
public class LevenshteinDistance {
 private static int minimum(int a, int b, int c) {
 if (a < b && a < c) {
 return a;
 } else if (b < a && b < c) {
 return b;
 } else {
 return c;
 }
 }

 private static int calculate_distance(String a, String b) {
 int len_a = a.length() + 1;
 int len_b = b.length() + 1;
 int[][] distance_mat = new int[len_a][len_b];
 for (int i = 0; i < len_a; i++) {
 distance_mat[i][0] = i;
 }
 for (int j = 0; j < len_b; j++) {
 distance_mat[0][j] = j;
 }
 for (int i = 0; i < len_a; i++) {
 for (int j = 0; j < len_b; j++) {
 int cost;
 if (a.charAt(i) == b.charAt(j)) {
 cost = 0;
 } else {
 cost = 1;
 }
 distance_mat[i][j] =
 minimum(distance_mat[i - 1][j], distance_mat[i - 1][j - 1], distance_mat[i][j - 1])
 + cost;
 }
 }
 return distance_mat[len_a - 1][len_b - 1];
 }

 public static void main(String[] args) {
 String a = ""; // enter your string here
 String b = ""; // enter your string here

 System.out.print("Levenshtein distance between " + a + " and " + b + " is: ");
 System.out.println(calculate_distance(a, b));
 }
}