cleaning up and organizing old problems (builtin)

src/builtin_structures/find_edit_distance.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python
+
+__author__ = "bt3"
+
+
+''' computes the edit distance between two strings '''
+
+
+def find_edit_distance(str1, str2):
+    '''
+    >>> s = 'sunday'
+    >>> t = 'saturday'
+    >>> find_edit_distance(s, t)
+    3
+    '''
+
+	m = len(str1)
+	n = len(str2)
+	diff = lambda c1, c2: 0 if c1 == c2 else 1
+
+	E = [[0] * (n + 1) for i in range(m + 1)]
+
+	for i in range(m + 1):
+		E[i][0] = i
+
+    for j in range(1, n + 1):
+		E[0][j] = j
+
+    for i in range(1, m + 1):
+		for j in range(1, n + 1):
+			E[i][j] = min(E[i-1][j] + 1, E[i][j-1] + 1, E[i-1][j-1] + diff(str1[i-1], str2[j-1]))
+
+    return E[m][n]
+
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+
+
+
+