Merge d94adb1 into 3f9aa45

README.md

@@ -302,7 +302,8 @@ If you want to uninstall algorithms, it is as simple as:
     - [longest_common_prefix](algorithms/strings/longest_common_prefix.py)
     - [rotate](algorithms/strings/rotate.py)
     - [first_unique_char](algorithms/strings/first_unique_char.py)
-    - [repeat_substring](algorithms/strings/repeat_substring.py)     
+    - [repeat_substring](algorithms/strings/repeat_substring.py)
+    - [levenshtein distance](algorithms/strings/levenshtein.py)
 - [tree](algorithms/tree)
     - [bst](algorithms/tree/bst)
         - [array_to_bst](algorithms/tree/bst/array_to_bst.py)

README_CN.md

@@ -259,6 +259,7 @@ pip3 uninstall -y algorithms
     - [reverse_words：反转单词](algorithms/strings/reverse_words.py)
     - [roman_to_int：罗马数转换整数](algorithms/strings/roman_to_int.py)
     - [word_squares：单词平方](algorithms/strings/word_squares.py)
+    - [levenshtein distance](algorithms/strings/levenshtein.py)
 - [tree：树](algorithms/tree)
     - [segment-tree：线段树](algorithms/tree/segment_tree)
         - [segment_tree：线段树](algorithms/tree/segment_tree/segment_tree.py)

README_FR.md

@@ -301,7 +301,8 @@ Si vous voulez désinstaller le paquet algorithms, il suffit de procéder comme
     - [longest_common_prefix](algorithms/strings/longest_common_prefix.py)
     - [rotate](algorithms/strings/rotate.py)
     - [first_unique_char](algorithms/strings/first_unique_char.py)
-    - [repeat_substring](algorithms/strings/repeat_substring.py)     
+    - [repeat_substring](algorithms/strings/repeat_substring.py)   
+    - [levenshtein distance](algorithms/strings/levenshtein.py)  
 - [tree](algorithms/tree)
     - [bst](algorithms/tree/tree/bst)
         - [array2bst](algorithms/tree/bst/array2bst.py)

README_GE.md

@@ -291,6 +291,7 @@ Um das Projekt zu deinstallieren tippen Sie folgendes:
     - [reverse_words](algorithms/strings/reverse_words.py)
     - [roman_to_int](algorithms/strings/roman_to_int.py)
     - [word_squares](algorithms/strings/word_squares.py)
+    - [levenshtein distance](algorithms/strings/levenshtein.py)
 - [tree](algorithms/tree)
     - [bst](algorithms/tree/tree/bst)
         - [array2bst](algorithms/tree/bst/array2bst.py)

README_JP.md

@@ -285,6 +285,7 @@ if __name__ == "__main__":
     - [reverse_words](algorithms/strings/reverse_words.py)
     - [roman_to_int](algorithms/strings/roman_to_int.py)
     - [word_squares](algorithms/strings/word_squares.py)
+    - [levenshtein distance](algorithms/strings/levenshtein.py)
 - [tree : 木構造](algorithms/tree)
     - [bst](algorithms/tree/tree/bst)
         - [array2bst](algorithms/tree/bst/array2bst.py)

README_KR.md

@@ -279,6 +279,7 @@ if __name__ == "__main__":
     - [reverse_words](algorithms/strings/reverse_words.py)
     - [roman_to_int](algorithms/strings/roman_to_int.py)
     - [word_squares](algorithms/strings/word_squares.py)
+    - [levenshtein distance](algorithms/strings/levenshtein.py)
 - [tree : 트리](algorithms/tree)
     - [bst : 이진 탐색 트리](algorithms/tree/tree/bst)
         - [array2bst](algorithms/tree/bst/array2bst.py)

README_PTBR.md

@@ -289,6 +289,7 @@ Se você deseja desinstalar os algoritmos, é tão simples quanto:
     - [caesar_cipher](algorithms/strings/caesar_cipher.py)
     - [contain_string](algorithms/strings/contain_string.py)
     - [count_binary_substring](algorithms/strings/count_binary_substring.py)
+    - [levenshtein distance](algorithms/strings/levenshtein.py)
 - [tree](algorithms/tree)
     - [bst](algorithms/tree/tree/bst)
         - [array2bst](algorithms/tree/bst/array2bst.py)

algorithms/strings/levenshtein.py

@@ -0,0 +1,54 @@
+"""Levenshtein Distance.
+
+In information theory, linguistics and computer science,
+the Levenshtein distance is a string metric for measuring the difference
+between two sequences. Informally, the Levenshtein distance between two words
+is the minimum number of single-character edits (insertions, deletions or
+substitutions) required to change one word into the other.
+It is named after the Soviet mathematician Vladimir Levenshtein, who considered
+this distance in 1965.[1]
+
+Levenshtein distance may also be referred to as edit distance, although that
+term may also denote a larger family of distance metrics.[2]:32 It is closely
+related to pairwise string alignments.
+
+https://en.wikipedia.org/wiki/Levenshtein_distance (27/09/2018)
+"""
+
+
+def levenshtein(A, B):
+    """
+    Return the edit distance between two strings.
+
+    Example:
+    >>> from levenshtein import levenshtein
+    >>> levenshtein("Star Wars", "Star Trek")
+    >>> 4
+    """
+    m = len(A)
+    n = len(B)
+    M = []
+
+    for x in range(m+1):
+        M.append([])
+        for y in range(n+1):
+            M[x].append((0))
+
+    for i in range(0, m+1):
+        M[i][0] = i
+
+    for j in range(0, n+1):
+        M[0][j] = j
+
+    for x in range(1, m+1):
+        for y in range(1, n+1):
+            if A[x-1] == B[y-1]:
+                cost = 0
+            else:
+                cost = 1
+
+            M[x][y] = min((M[x-1][y-1] + cost,
+                           M[x-1][y] + 1,
+                           M[x][y-1] + 1,))
+
+    return(M[m][n])