C# Programming

For one-to-many relationships with concurrent access, combining ConcurrentDictionary with ConcurrentBag (or List) provides thread-safe multi-value storage per key.

LinkedList<T> provides O(1) AddFirst(), AddLast(), RemoveFirst(), and RemoveLast() operations. List<T> requires O(n) for head removals due to reindexing.

SortedList<K,V> maintains sorted order by keys and allows O(1) index-based access. SortedSet<T> doesn't support indexing.

HashSet<T> uses hash-based lookup for Contains(), achieving O(1) average-case time complexity, with O(n) worst-case in case of hash collisions.

MemoryCache provides LRU-style eviction and memory management policies. Basic collections don't have built-in LRU functionality.

Peek() returns the top element without modifying the stack. Pop() removes and returns it. Peek() throws InvalidOperationException if the stack is empty.

SortedDictionary<K,V> uses a red-black tree (binary search tree) for O(log n) operations. SortedSet<T> also uses BST but for single values.

Queue<T> provides FIFO semantics with O(1) Enqueue() and Dequeue() operations. Stack<T> is LIFO, and LinkedList operations vary.

HashSet<T> requires O(n) space to store n unique elements in the underlying hash table structure.

ToList() converts the Dictionary's KeyValuePair<K,V> enumeration into a List<KeyValuePair<K,V>>. ToArray() would create an array instead.