Initial commit

python/Algorithms/string_distances.py

@@ -0,0 +1,34 @@
+# https://en.wikipedia.org/wiki/Levenshtein_distance
+import time
+import random
+
+
+def levenstein_distance(a, b):
+    m = len(a)
+    n = len(b)
+    dp = [[0] * (n + 1) for i in range(m + 1)]
+    for i in range(m + 1):
+        dp[i][0] = i
+    for j in range(n + 1):
+        dp[0][j] = j
+    for i in range(m):
+        for j in range(n):
+            if a[i] == b[j]:
+                dp[i + 1][j + 1] = dp[i][j]
+            else:
+                dp[i + 1][j + 1] = 1 + min(dp[i][j], dp[i + 1][j], dp[i][j + 1])
+    return dp[m][n]
+
+
+def test():
+    start = time.time()
+    print(levenstein_distance('abc', 'ab'))
+    print(levenstein_distance(random_string(1000), random_string(1000)))
+    print(time.time() - start)
+
+
+def random_string(len):
+    return ''.join(random.choice('ab') for _ in range(len))
+
+
+test()