Added problem.

Author: das-jishu

Assessments/special-strings.py

@@ -0,0 +1,44 @@
+
+# SPECIAL STRINGS
+
+# O(N * M) time and O(N * M) space
+def specialStrings(strings):
+    # Write your code here.
+    trie = Trie()
+	for string in strings:
+		trie.buildTrie(string)
+		
+	specials = []
+	for string in strings:
+		if checkSpecial(string, trie.root, 0, 0, trie):
+			specials.append(string)
+			
+	return specials
+		
+def checkSpecial(string, node, index, count, trie):
+	letter = string[index]
+	if letter not in node:
+		return False
+	
+	if index == len(string) - 1:
+		return trie.endSymbol in node[letter] and count > 0
+	
+	if trie.endSymbol in node[letter]:
+		remainingSpecial = checkSpecial(string, trie.root, index + 1, count + 1, trie)
+		if remainingSpecial:
+			return True
+		
+	return checkSpecial(string, node[letter], index + 1, count, trie)
+
+class Trie:
+	def __init__(self):
+		self.root = {}
+		self.endSymbol = "*"
+		
+	def buildTrie(self, string):
+		current = self.root
+		for letter in string:
+			if letter not in current:
+				current[letter] = {}
+			current = current[letter]
+		current[self.endSymbol] = True