Introduction to Tries

In computer science, a trie (pronounced "try") is a tree-like data structure that is commonly used to store and retrieve strings efficiently.

The word "trie" is derived from the word "retrieval", indicating its purpose of efficiently retrieving data.

Structure of a Trie

A trie is composed of a series of nodes, where each node represents a character in a string. The nodes are connected in a tree-like structure, with each node having links to its possible children.

Let's visualize a simple example of a trie structure that stores the words "apple", "app", "apply", and "application":

Node Characteristics

Each node in a trie has the following characteristics:

• A value that represents the character it represents
• A boolean flag indicating whether it marks the end of a string
• Links to its children nodes, which are other nodes representing the next characters in the string

Uses of Tries

Tries are commonly used for tasks such as:

• Autocomplete suggestions
• Spell checking
• Finding words with a common prefix
• IP routing

Implementation of Tries

Tries can be implemented using various programming languages. Here's an example of a trie implementation in C++:

1#include <iostream>
2#include <unordered_map>
3
4struct TrieNode {
5  std::unordered_map<char, TrieNode*> children;
6  bool isEndOfWord;
7};
8
9void insert(TrieNode* root, const std::string& word) {
10  TrieNode* current = root;
11
12  for (const char& c : word) {
13    if (current->children.find(c) == current->children.end()) {
14      current->children[c] = new TrieNode();
15    }
16
17    current = current->children[c];
18  }
19
20  current->isEndOfWord = true;
21}
22
23bool search(TrieNode* root, const std::string& word) {
24  TrieNode* current = root;
25
26  for (const char& c : word) {
27    if (current->children.find(c) == current->children.end()) {
28      return false;
29    }
30
31    current = current->children[c];
32  }
33
34  return current->isEndOfWord;
35}
36
37int main() {
38  TrieNode* root = new TrieNode();
39
40  insert(root, "apple");
41  insert(root, "app");
42  insert(root, "apply");
43  insert(root, "application");
44
45  std::cout << "Search for 'apple': " << (search(root, "apple") ? "Found" : "Not found") << std::endl;
46  std::cout << "Search for 'apply': " << (search(root, "apply") ? "Found" : "Not found") << std::endl;
47  std::cout << "Search for 'banana': " << (search(root, "banana") ? "Found" : "Not found") << std::endl;
48
49  return 0;
50}

In this implementation, we first define a TrieNode struct that represents a node in the trie. It contains a std::unordered_map to store the links to its children nodes. The insert function is used to insert a word into the trie, and the search function is used to search for a word in the trie.

Try running the above C++ code example to see how the trie data structure works for storing and searching for words.

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#include <iostream>

using namespace std;

​

int main() {

  // Replace with your C++ logic here

}