added levenshtein distance dp implementation

kv19971 · kv19971 · commit 0957f33275b9 · 2017-09-29T00:43:08.000+08:00
diff --git a/Dynamic Programming/Levenshtein_distance.java b/Dynamic Programming/Levenshtein_distance.java
@@ -0,0 +1,55 @@
+/**
+ *
+ * @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 Levenshtein_distance{
+	private 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;
+		}
+	}
+	public int calculate_distance(String a, String b){
+		len_a = a.length() + 1;
+		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; i < 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));
+
+
+	}
+}
