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Author: Ram-95

Trie_using_Array.py

@@ -0,0 +1,63 @@
+#Trie Data structure
+class TrieNode:
+    def __init__(self):
+        self.children = [None] * 26
+        self.isEnd = False
+
+class Trie:
+    '''Creates a Trie Data Stucture.'''
+    def __init__(self):
+        self.root = TrieNode()
+
+    def _charToIndex(self, ch):
+    '''Helper Function to find the index of a character in the range [0,25].'''
+        return ord(ch) - ord('a')
+
+    def insert(self, key):
+    '''Inserts a word/key into the Trie.'''    
+        t_root = self.root
+        length = len(key)
+        for i in range(length):
+            idx = self._charToIndex(key[i])
+
+            if not t_root.children[idx]:
+                t_root.children[idx] = TrieNode()
+            t_root = t_root.children[idx]
+
+        t_root.isEnd = True
+
+    def search(self, key):
+    '''Returns True is given word is present in the Trie, else returns False.'''
+        t_root = self.root
+        length = len(key)
+        for i in range(length):
+            idx = self._charToIndex(key[i])
+            if not t_root.children[idx]:
+                return False
+            t_root = t_root.children[idx]
+
+        return t_root != None and t_root.isEnd
+
+    def startsWith(self, key):
+    '''Returns True if given word is present as a prefix in the Trie, else returns False.'''
+        t_root = self.root
+        length = len(key)
+        for i in range(length):
+            idx = self._charToIndex(key[i])
+            if not t_root.children[idx]:
+                return False
+            t_root = t_root.children[idx]
+
+        return True
+        
+
+#Driver Code
+keys = ['the', 'their', 'there', 'they', 'these', 'thesis', 'apple', 'appy', 'cat', 'catfish', 'cattle', 'cats']
+
+#Creating a Trie Object
+t = Trie()
+
+#Inserting Keys into the Trie
+for key in keys:
+    t.insert(key)
+