public void TestingDFSPostOrder(int[] arr, int[] expected)
{
var binarySearchTree = new BinarySearchTree();
for (int i = 0; i < arr.Length; i++)
{
binarySearchTree.Insert(arr[i]);
}
List <int> list = new List <int>();
var depthFirstSearch = new DepthFirstSearch();
var result = depthFirstSearch.DFSPostOrder(binarySearchTree.root, list);
Assert.AreEqual(expected, result);
}