unordered_map

---

1. Implementing a Key-Value Cache

#include <unordered_map>

class KVCache {
public:
    void put(const string& key, const string& value) { cache[key] = value; }
    string get(const string& key) { return cache[key]; }
private:
    unordered_map<string, string> cache;
};

2. Counting Occurrences of Words in Text

#include <unordered_map>

unordered_map<string, int> word_counts;
for (const string& word : words) {
    word_counts[word]++;
}

3. Grouping Items by Category

#include <unordered_map>

unordered_map<string, vector<string>> items_by_category;
for (const string& item : items) {
    items_by_category[category(item)].push_back(item);
}

4. Creating a Graph Data Structure

#include <unordered_map>

unordered_map<int, vector<int>> graph;

5. Implementing a Dictionary

#include <unordered_map>

unordered_map<string, string> dictionary;
string translation = dictionary["word"];

6. Storing User Preferences

#include <unordered_map>

unordered_map<string, string> user_preferences;
string preference = user_preferences["username"];

7. Caching Database Queries

#include <unordered_map>

unordered_map<string, string> query_cache;
string result = query_cache[query];

8. Representing Sparse Matrices

#include <unordered_map>

unordered_map<pair<int, int>, double> sparse_matrix;
double value = sparse_matrix[{i, j}];

9. Creating a Set of Unique Elements

#include <unordered_map>

unordered_map<int, bool> unique_elements;
if (unique_elements[element]) {
    // Element is already in the set
}

10. Implementing a Bloom Filter

#include <unordered_map>

unordered_map<int, bool> bloom_filter;

11. Tracking Objects in a Game

#include <unordered_map>

unordered_map<int, GameObject*> game_objects;
GameObject* player = game_objects[player_id];

12. Creating a Lookup Table

#include <unordered_map>

unordered_map<string, int> lookup_table;
int value = lookup_table["key"];

13. Representing a Trie Data Structure

#include <unordered_map>

unordered_map<char, TrieNode*> trie;

14. Implementing a Hash Table

#include <unordered_map>

unordered_map<int, string> hash_table;

15. Storing Metadata for File Paths

#include <unordered_map>

unordered_map<string, FileMetadata> file_metadata;
FileMetadata metadata = file_metadata["path"];

16. Representing a Data Dictionary

#include <unordered_map>

unordered_map<string, DataColumn> data_dictionary;

17. Implementing a Symbol Table for a Compiler

#include <unordered_map>

unordered_map<string, Symbol> symbol_table;

18. Tracking Connections in a Network

#include <unordered_map>

unordered_map<int, vector<int>> connections;

19. Representing a Directed Graph

#include <unordered_map>

unordered_map<int, vector<int>> directed_graph;

20. Creating a Custom Index for a Database

#include <unordered_map>

unordered_map<string, vector<int>> custom_index;

21. Storing User Session Data

#include <unordered_map>

unordered_map<string, SessionData> session_data;

22. Tracking Recent Activity in an Application

#include <unordered_map>

unordered_map<string, Timestamp> recent_activity;

23. Implementing a LRU Cache

#include <unordered_map>

unordered_map<int, pair<int, int>> lru_cache;

24. Representing a Sparse Vector

#include <unordered_map>

unordered_map<int, double> sparse_vector;

25. Tracking Progress in a Game

#include <unordered_map>

unordered_map<string, int> game_progress;

26. Storing Configuration Settings

#include <unordered_map>

unordered_map<string, string> config_settings;

27. Representing a Sudoku Puzzle

#include <unordered_map>

unordered_map<pair<int, int>, int> sudoku_puzzle;

28. Creating a Calendar

#include <unordered_map>

unordered_map<Date, vector<Event>> calendar;

29. Tracking User Rankings

#include <unordered_map>

unordered_map<string, int> user_rankings;

30. Representing a Map of Locations

#include <unordered_map>

unordered_map<string, Location> map_of_locations;

31. Creating a File System

#include <unordered_map>

unordered_map<string, File> file_system;

32. Representing a Social Network

#include <unordered_map>

unordered_map<int, vector<int>> social_network;

33. Implementing a Custom Data Type

#include <unordered_map>

struct CustomDataType