Stashbox by Peter Csajtai

<PackageReference Include="Stashbox" Version="3.6.3-preview-636" />

.NET API 178,176 bytes

Tree<TValue>

sealed class Tree<TValue>

public bool IsEmpty { get; }

public Tree()

public void Add(int key, TValue value)

public TValue GetOrDefault(int key)

public IEnumerable<TValue> Walk()