/// <summary>
/// Return the next lower key-value pair before given key in this dictionary.
/// Time complexity: O(log(n)).
/// </summary>
/// <returns>Null if the given key does'nt exist or previous key does'nt exist.</returns>
public KeyValuePair <K, V> NextLower(K key)
{
var prev = binarySearchTree.NextLower(new SortedDictionaryNode <K, V>(key, default(V)));
if (prev == null)
{
return(default(KeyValuePair <K, V>));
}
return(new KeyValuePair <K, V>(prev.Key, prev.Value));
}
/// <summary>
/// Return the next lower value before given value in this HashSet.
/// Time complexity: O(log(n)).
/// </summary>
/// <returns>Null if the given value does'nt exist or previous value does'nt exist.</returns>
public T Previous(T value)
{
return(binarySearchTree.NextLower(value));
}