Edit-Distantance DP

Author: roushansingh96

Dynamic Programming/EditDistance.java

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+/* A Dynamic Programming based Java program to find minimum number operations to convert String1  to String2 */ 
+class EditDistance 
+{ 
+	static int min(int x,int y,int z) 
+	{ 
+		if (x <= y && x <= z) 
+			return x; 
+		if (y <= x && y <= z) 
+			return y; 
+		else 
+			return z; 
+	} 
+
+	static int editDistDP(String str1, String str2, int m, int n) 
+	{ 
+		// Create a table to store results of subproblems 
+		int dp[][] = new int[m+1][n+1]; 
+	
+		// Fill d[][] in bottom up manner 
+		for (int i=0; i<=m; i++) 
+		{ 
+			for (int j=0; j<=n; j++) 
+			{ 
+				// If first string is empty, only option is to 
+				// insert all characters of second string 
+				if (i==0) 
+					dp[i][j] = j; // Min. operations = j 
+	
+				// If second string is empty, only option is to 
+				// remove all characters of second string 
+				else if (j==0) 
+					dp[i][j] = i; // Min. operations = i 
+	
+				// If last characters are same, ignore last char 
+				// and recur for remaining string 
+				else if (str1.charAt(i-1) == str2.charAt(j-1)) 
+					dp[i][j] = dp[i-1][j-1]; 
+	
+				// If the last character is different, consider all 
+				// possibilities and find the minimum 
+				else
+					dp[i][j] = 1 + min(dp[i][j-1], // Insert 
+							   dp[i-1][j], // Remove 
+							   dp[i-1][j-1]); // Replace 
+			} 
+		} 
+
+		return dp[m][n]; 
+	} 
+
+	public static void main(String args[]) 
+	{ 
+		String str1 = "Rohan"; //1st String that need to be converted to 2nd String
+		String str2 = "Roushan"; //2nd String
+		System.out.println( editDistDP( str1 , str2 , str1.length(), str2.length()) ); 
+	} 
+}
+