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Trie with Insert, Search, and startsWith Methods

Certification: Intermediate Level Accuracy: 0% Submissions: 0 Points: 12

Write a C# program to implement a Trie data structure with the following methods: 1. `Insert(word)`: Inserts a word into the trie. 2. `Search(word)`: Returns true if the word exists in the trie, false otherwise. 3. `StartsWith(prefix)`: Returns true if there is a word in the trie that starts with the given prefix, false otherwise.

Example 1
    
  
  • Input: 
["Trie", "insert", "search", "search", "startsWith", "insert", "search"]

    [[], ["apple"], ["apple"], ["app"], ["app"], ["app"], ["app"]]
    • 
  
  • Output: [null, null, true, false, true, null, true]
    • 
  
  • Explanation: 
    
      
      
    • Trie trie = new Trie();
      • 
      
    • trie.Insert("apple");
      • 
      
    • trie.Search("apple");   // returns true
      • 
      
    • trie.Search("app");     // returns false
      • 
      
    • trie.StartsWith("app"); // returns true
      • 
      
    • trie.Insert("app");
      • 
      
    • trie.Search("app");     // returns true
      • 
    
    
  
    •
Example 2
    
  
  • Input: 
["Trie", "insert", "insert", "insert", "search", "startsWith", "search"]

    [[], ["hello"], ["world"], ["hi"], ["hello"], ["wo"], ["hey"]]
    • 
  
  • Output: [null, null, null, null, true, true, false]
    • 
  
  • Explanation: 
    
      
      
    • Trie trie = new Trie();
      • 
      
    • trie.Insert("hello");
      • 
      
    • trie.Insert("world");
      • 
      
    • trie.Insert("hi");
      • 
      
    • trie.Search("hello");    // returns true
      • 
      
    • trie.StartsWith("wo");   // returns true
      • 
      
    • trie.Search("hey");      // returns false
      • 
    
    
  
    •
Constraints
    
  
  • 1 ≤ word.length, prefix.length ≤ 2000
    • 
  
  • word and prefix consist only of lowercase English letters
    • 
  
  • At most 3 * 10^4 calls in total will be made to insert, search, and startsWith
    • 
  
  • Time Complexity: O(m) for all operations, where m is the key length
    • 
  
  • Space Complexity: O(n * m) where n is the number of keys and m is the average key length
    •
ArraysTrie Tech MahindraSamsung
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Hint
Solution

Solution Hints

    
  
  • Use a tree-like data structure where each node represents a single character
    • 
  
  • Each node should contain links to child nodes for each possible character
    • 
  
  • Use a boolean flag in each node to mark the end of a word
    • 
  
  • For the insert operation, create nodes for each character if they don't exist
    • 
  
  • For the search operation, follow the path in the trie and check if the last node is marked as the end of a word
    • 
  
  • For the startsWith operation, just follow the path in the trie without checking the end-of-word flag
    •

Steps to solve by this approach:

 Step 1: Create a TrieNode class with an array of children nodes (one for each letter) and a boolean flag to mark the end of a word.
 Step 2: Implement the Trie class with a root TrieNode.
 Step 3: For insertion, traverse the trie character by character. If a node for the current character doesn't exist, create it.
 Step 4: After inserting all characters, mark the last node as the end of a word.
 Step 5: Create a helper method to find a node corresponding to a given string.
 Step 6: For search, find the node corresponding to the word and check if it's marked as the end of a word.
 Step 7: For startsWith, simply find the node corresponding to the prefix without checking the end-of-word flag.

Submitted Code :