add python implementaion of trie

classicalAlgos/tries/tries.py

@@ -0,0 +1,72 @@
+class Node:
+    def _init_(self):
+        self.children = [None] * 26
+        self.isEnd = False
+
+
+class Trie:
+    def _init_(self):
+        self.root = Node()
+
+    def createNode(self):
+        return Node()
+
+    def _convertCharToIndex(self, ch):
+        return ord(ch) - ord('a')
+
+    def insert(self, word):
+        # If key is not present, inserts it into trie, else just mark the word to be completed, by traversing the trie sequentially.
+        currentNode = self.root
+        for i in range(len(word)):
+            index = self._convertCharToIndex(word[i])
+
+            # if current character is not present
+            if not currentNode.children[index]:
+                currentNode.children[index] = self.createNode()
+            currentNode = currentNode.children[index]
+
+        # mark last node as completing a word
+        currentNode.isEnd = True
+
+    def search(self, word):
+        current_node = self.root
+        for i in range(len(word)):
+            index = self._convertCharToIndex(word[i])
+
+            # return false immediately if the current character is not present in the trie.
+            if not current_node.children[index]:
+                return False
+            current_node = current_node.children[index]
+
+        # even if the control reaches the end, then we have to check if a word ends here.
+        return current_node.isEnd
+
+# driver function here
+
+
+def main():
+    # take input of the number of words and the number of queries
+    n = int(input("Enter the number of words: "))
+    q = int(input("Enter the number of queries: "))
+
+    t = Trie()
+    print("Enter the words: ")
+    while (n > 0):
+        word = input().strip()
+        t.insert(word)
+        n -= 1
+
+    print("Enter the queries: ")
+    while (q > 0):
+        word = input().strip()
+        if t.search(word):
+            print("YES")
+        else:
+            print("NO")
+        q -= 1
+
+
+# the main function to run the script
+if __name__ == '__main__':
+    # print("1")
+    main()