unordered_map of pair and int

Here is an explanation for each step:

  1. Include the necessary header file: To use the unordered_map container in C++, you need to include the header file .

  2. Declare the unordered_map: To declare an unordered_map, you need to specify the key type and the value type enclosed in angle brackets. In this case, the key type is a pair and the value type is an integer. For example: unordered_map, int> myMap;

  3. Insert elements into the unordered_map: To insert elements into the unordered_map, you can use the insert() function or the [] operator. The key-value pairs are enclosed in curly braces. For example: myMap.insert({{1, 2}, 3}); myMap[{4, 5}] = 6;

  4. Access elements in the unordered_map: To access elements in the unordered_map, you can use the [] operator with the desired key. For example: int value = myMap[{1, 2}];

  5. Iterate over the unordered_map: To iterate over the elements in the unordered_map, you can use a range-based for loop. For example: for (const auto& pair : myMap) { // Accessing the key-value pair pair.first; // key pair.second; // value }

  6. Check if an element exists in the unordered_map: To check if a key exists in the unordered_map, you can use the find() function. If the key is found, the function returns an iterator pointing to the element. If the key is not found, the function returns an iterator pointing to the end of the unordered_map. For example: if (myMap.find({1, 2}) != myMap.end()) { // Key exists } else { // Key does not exist }

  7. Remove an element from the unordered_map: To remove an element from the unordered_map, you can use the erase() function with the desired key. For example: myMap.erase({1, 2});

  8. Check the size of the unordered_map: To check the size of the unordered_map (i.e., the number of elements it contains), you can use the size() function. For example: int size = myMap.size();

Note: The unordered_map container in C++ provides a way to store key-value pairs, where the keys are unique. It is implemented as a hash table, which allows for efficient insertion, deletion, and retrieval of elements based on their keys. The order of elements in the unordered_map is not guaranteed.