Day8

day8/Python/minimum_edit_distance.py

@@ -0,0 +1,47 @@
+"""
+ @author : imkaka
+ @date   : 31/12/2018
+
+"""
+
+import sys
+
+
+def min_edit_distance(str1, str2):
+    len1 = len(str1)
+    len2 = len(str2)
+
+    # Matrix inilization
+    dp = [[0 for i in range(len2 + 1)]
+          for j in range(len1 + 1)]
+
+    for i in range(1, len1 + 1):
+        dp[i][0] = i
+
+    for j in range(1, len2 + 1):
+        dp[0][j] = j
+
+    # Fill the DP matrix.
+
+    for j in range(1, len2 + 1):
+        for i in range(1, len1 + 1):
+            if(str1[i - 1] == str2[j - 1]):
+                dp[i][j] = dp[i - 1][j - 1]
+            else:
+                dp[i][j] = 1 + min(dp[i - 1][j - 1],
+                                   dp[i][j - 1],
+                                   dp[i - 1][j])
+    return dp[len1][len2]
+
+
+def main():
+
+    print("==================Minimum Edit Distance====================")
+    print()
+
+    print(min_edit_distance("kitten", "sitting"))
+    print(min_edit_distance("abcdef", "abcdhgikll"))
+
+
+if __name__ == '__main__':
+    main()

day8/README.md

@@ -8,9 +8,9 @@ Given two strings, and operations like replace, delete and add, write a program
 
 ## Example (source: [Wikipedia](https://en.wikipedia.org/wiki/Levenshtein_distance))
 
-For example, the (Minimum Edit) Levenshtein distance between `kitten` and 
-`sitting` is `3`, since the following three edits change one 
-into the other, and there is no way to do it with fewer than 
+For example, the (Minimum Edit) Levenshtein distance between `kitten` and
+`sitting` is `3`, since the following three edits change one
+into the other, and there is no way to do it with fewer than
 three edits:
 
 1. **k**itten → **s**itten (substitution of "s" for "k")
@@ -27,13 +27,13 @@ Mathematically, the Levenshtein distance between two strings `a` and `b` (of len
 
 ![def](https://wikimedia.org/api/rest_v1/media/math/render/svg/f0a48ecfc9852c042382fdc33c19e11a16948e85)
 
-where 
+where
 ![def](https://wikimedia.org/api/rest_v1/media/math/render/svg/52512ede08444b13838c570ba4a3fc71d54dbce9)
 is the indicator function equal to `0` when
 ![def](https://wikimedia.org/api/rest_v1/media/math/render/svg/231fda9ee578f0328c5ca28088d01928bb0aaaec)
 and equal to 1 otherwise, and
 ![def](https://wikimedia.org/api/rest_v1/media/math/render/svg/bdc0315678caad28648aafedb6ebafb16bd1655c)
-is the distance between the first `i` characters of `a` and the first 
+is the distance between the first `i` characters of `a` and the first
 `j` characters of `b`.
 
 Therefore, the minimum edit distance between `a` and `b` is the last element in the edit distance matrix
@@ -110,50 +110,50 @@ console.log(minEditDist('kitten', 'sitting'));
 * @date : 31/12/2018
 */
 
-#include<bits/stdc++.h> 
-using namespace std; 
-  
-int min(int x, int y, int z) 
-{ 
-    return min(min(x, y), z); 
-} 
-  
-int levenshtein_distance(string str1, string str2, int m, int n) 
-{ 
-    int ld[m+1][n+1]; 
-  
-    for (int i=0; i<=m; i++) 
-    { 
-        for (int j=0; j<=n; j++) 
-        { 
-            if (i==0) 
+#include<bits/stdc++.h>
+using namespace std;
+
+int min(int x, int y, int z)
+{
+    return min(min(x, y), z);
+}
+
+int levenshtein_distance(string str1, string str2, int m, int n)
+{
+    int ld[m+1][n+1];
+
+    for (int i=0; i<=m; i++)
+    {
+        for (int j=0; j<=n; j++)
+        {
+            if (i==0)
                 ld[i][j] = j;
-  
-            else if (j==0) 
+
+            else if (j==0)
                 ld[i][j] = i;
-  
- 
-            else if (str1[i-1] == str2[j-1]) 
-                ld[i][j] = ld[i-1][j-1]; 
-  
+
+
+            else if (str1[i-1] == str2[j-1])
+                ld[i][j] = ld[i-1][j-1];
+
             else
-                ld[i][j] = 1 + min(ld[i][j-1], ld[i-1][j], ld[i-1][j-1]);  
-        } 
-    } 
-  
-    return ld[m][n]; 
-} 
-  
-int main() 
-{ 
+                ld[i][j] = 1 + min(ld[i][j-1], ld[i-1][j], ld[i-1][j-1]);
+        }
+    }
+
+    return ld[m][n];
+}
+
+int main()
+{
     string str1,str2;
     cin >> str1 >> str2;
-  
-    cout << levenshtein_distance(str1, str2, str1.length(), str2.length()); 
-  
-    return 0; 
+
+    cout << levenshtein_distance(str1, str2, str1.length(), str2.length());
+
+    return 0;
 }
-``` 
+```
 
 ### C Implementation
 
@@ -216,6 +216,62 @@ int main()
     return 0;
 }
 
+```
+
+## Python Implementation
+
+### [Solution](./Python/minimum_edit_distance.py)
+
+```py
+
+"""
+ @author : imkaka
+ @date   : 31/12/2018
+
+"""
+
+import sys
+
+
+def min_edit_distance(str1, str2):
+    len1 = len(str1)
+    len2 = len(str2)
+
+    # Matrix inilization
+    dp = [[0 for i in range(len2 + 1)]
+          for j in range(len1 + 1)]
+
+    for i in range(1, len1 + 1):
+        dp[i][0] = i
+
+    for j in range(1, len2 + 1):
+        dp[0][j] = j
+
+    # Fill the DP matrix.
+
+    for j in range(1, len2 + 1):
+        for i in range(1, len1 + 1):
+            if(str1[i - 1] == str2[j - 1]):
+                dp[i][j] = dp[i - 1][j - 1]
+            else:
+                dp[i][j] = 1 + min(dp[i - 1][j - 1],
+                                   dp[i][j - 1],
+                                   dp[i - 1][j])
+    return dp[len1][len2]
+
+
+def main():
+
+    print("==================Minimum Edit Distance====================")
+    print()
+
+    print(min_edit_distance("kitten", "sitting"))
+    print(min_edit_distance("abcdef", "abcdhgikll"))
+
+
+if __name__ == '__main__':
+    main()
+
 ``` 
 
 ## Java Implementation
@@ -280,4 +336,5 @@ public class Levenshtein {
         System.out.println("Minimum no of operations are "+dist);
     }
 }
+
 ```