From 9799fb829bfefdeb28848cb43ca918f5058d4345 Mon Sep 17 00:00:00 2001
From: kvadrik <41710943+kvadrik@users.noreply.github.com>
Date: Sun, 1 Sep 2019 03:09:59 +0300
Subject: [PATCH] Create 6_Damerau_Levenshtein_distance.py

---
 6_Damerau_Levenshtein_distance.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 6_Damerau_Levenshtein_distance.py

diff --git a/6_Damerau_Levenshtein_distance.py b/6_Damerau_Levenshtein_distance.py
new file mode 100644
index 0000000..bb09386
--- /dev/null
+++ b/6_Damerau_Levenshtein_distance.py
@@ -0,0 +1,22 @@
+# write a program that calculates Damerau-Levenshtein distance between two strings
+
+def dam_lev(a, b, i, j):
+    la = len(a)
+    lb = len(b)
+    if i == 0 and j == 0:
+        return 0
+    else:
+        res = la + lb + 1
+        if i > 0:
+            res = min (res, 1 + dam_lev(a, b, i-1, j))
+        if j > 0:
+            res = min (res, 1 + dam_lev(a, b, i, j-1))
+        if i > 0 and j > 0:
+            res = min (res, (a[i-1] != b[j-1]) + dam_lev(a, b, i-1, j-1))
+            if i > 1 and j > 1 and a[i-1] == b[j-2] and a[i-2] == b[j-1]:
+                res = min (res, 1 + dam_lev(a, b, i-2, j-2))
+        return res
+        
+w1 = input("Enter the first word: ")
+w2 = input("Enter the second word: ")
+print ("The distance between " + w1 + " and " + w2 + " is " + str(dam_lev(w1, w2, len(w1), len(w2))))