Merge pull request #843 from PrashantVIT1/master

Trie in Python

Author: noviicee

Trie/Trie_add_Search_using_dict.py

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+"""
+Purpose:
+
+Implementation of Trie has been asked in my interviews like in Google
+Store word in Dictionary
+Search word in the dictionary returns True if exist
+Stores words in a compressed manner
+"""
+"""
+Inputs:
+1nd line no of word you want to store in Trie (int)
+2rd line to (2+1st line input)th line (string)
+Next line enter number of words want to search
+then enter strings in each line
+
+"""
+class Trie:
+    root = {} #main dictionary of Trie
+    
+    def add(self, word): # This funtion adds new word to Trie
+        cur = self.root  # cur is iterator to check whether new key/paths are required to add new word and root is main dictionary
+        
+        for ch in word: # ch is all the charactors in the word 
+            if ch not in cur: # if charactor is not present add new key/path initiate it empty
+                cur[ch] = {}  
+            cur = cur[ch]    # now go to the key that was created or was present
+        cur['*'] = True   # set * key to true at the end of each word
+        #so larger the word the dictionary nesting will take place and * key represant the end state of the word
+        
+    def search(self,word): # This function searches whether the word is presant or not presant
+        cur = self.root  #cur is iterator to check whether new key/paths are presant or not
+        
+        for ch in word:    # ch is all the charactors in the word 
+            if ch not in cur:  # if ch is not found in cur that means word not presant so result is false
+                return False
+            cur = cur[ch] #if ch present then go till the end unless it becomes false
+        if '*' in cur: # if * key not present that means words is prefix of a word that is present but word is not Present
+            return True
+        else:
+            return False
+# dynamic input 
+n2 = int(input("No of words to be Added:\n")) 
+print("enter words:")
+words = []
+checks = []
+for j in range(n2):
+    words.append(input())
+n3 = int(input("No of words to be searched:\n"))
+print("enter words:")
+for j in range(n3):
+    checks.append(input())
+
+        
+
+"""
+Time complexity :
+Insert: O(word Length)
+Search: O(word Length)
+
+Space complexity :
+Insert: O(1)
+Search: O(1)
+
+Storages required for storing words:
+if no word has same prefix the required (total word length+1)*(char size)
+
+"""
+dictionary = Trie() # Trie object created
+
+
+for k in words:
+    dictionary.add(k) # adding word in Trie from words list
+for k in checks:
+    print(dictionary.search(k)) # printing Searched word results if present then prints True if not present then returns False