Create lexicographically-smallest-equivalent-string.py

Author: kamyu104

Python/lexicographically-smallest-equivalent-string.py

@@ -0,0 +1,36 @@
+# Time:  O(nlog*n) ~= O(n), n is the length of S
+# Space: O(n)
+
+class UnionFind(object):
+    def __init__(self, n):
+        self.set = range(n)
+
+    def find_set(self, x):
+        if self.set[x] != x:
+            self.set[x] = self.find_set(self.set[x])  # path compression.
+        return self.set[x]
+
+    def union_set(self, x, y):
+        x_root, y_root = map(self.find_set, (x, y))
+        if x_root == y_root:
+            return False
+        self.set[max(x_root, y_root)] = min(x_root, y_root)
+        return True
+    
+
+class Solution(object):
+    def smallestEquivalentString(self, A, B, S):
+        """
+        :type A: str
+        :type B: str
+        :type S: str
+        :rtype: str
+        """
+        union_find = UnionFind(26)
+        for i in xrange(len(A)):
+            union_find.union_set(ord(A[i])-ord('a'), ord(B[i])-ord('a'));
+        result = []
+        for i in xrange(len(S)):
+            parent = union_find.find_set(ord(S[i])-ord('a'));
+            result.append(chr(parent+ord('a')))
+        return "".join(result)