public void PreviousShouldBeAbleToWalkTheTreeBackward()
{
int seed = 12345;
int RandomNext()
{
seed = (seed * 69069) + 12345;
return((seed >> 16) & 0x7FFF);
}
WeightedRedBlackTree <int, int> tree = new WeightedRedBlackTree <int, int>();
List <int> keys = new List <int>();
for (int i = 0; i < 500; i++)
{
int key = RandomNext();
keys.Add(key);
tree.Add(key, i);
if (IsFibonacci(i))
{
List <WeightedRedBlackTreeNode <int, int> > actualNodes = new List <WeightedRedBlackTreeNode <int, int> >();
for (WeightedRedBlackTreeNode <int, int> node = tree.MaximumNode; node != null; node = node.Previous())
{
actualNodes.Add(node);
}
int[] actualKeys = actualNodes.Select(n => n.Key).ToArray();
int[] expectedKeys = keys.OrderByDescending(k => k).ToArray();
CollectionAssert.AreEqual(actualKeys, expectedKeys);
}
}
}
public void ShouldBeAbleToFindMinimaAndMaxima()
{
int seed = 12345;
int RandomNext()
{
seed = (seed * 69069) + 12345;
return((seed >> 16) & 0x7FFF);
}
WeightedRedBlackTree <int, int> tree = new WeightedRedBlackTree <int, int>();
Assert.That(tree.MinimumKey, Is.EqualTo(default(int)));
Assert.That(tree.MaximumKey, Is.EqualTo(default(int)));
Assert.That(tree.MinimumNode, Is.Null);
Assert.That(tree.MaximumNode, Is.Null);
List <int> keys = new List <int>();
for (int i = 0; i < 500; i++)
{
int key = RandomNext();
keys.Add(key);
tree.Add(key, i);
int expectedMinimum = keys.Min();
int actualMinimum = tree.MinimumKey;
Assert.That(expectedMinimum, Is.EqualTo(actualMinimum));
WeightedRedBlackTreeNode <int, int> actualMinimumNode = tree.MinimumNode;
Assert.That(expectedMinimum, Is.EqualTo(actualMinimumNode.Key));
int expectedMaximum = keys.Max();
int actualMaximum = tree.MaximumKey;
Assert.That(expectedMaximum, Is.EqualTo(actualMaximum));
WeightedRedBlackTreeNode <int, int> actualMaximumNode = tree.MaximumNode;
Assert.That(expectedMaximum, Is.EqualTo(actualMaximumNode.Key));
}
}
public void CanCopyToSpecialCaseTrees()
{
{
WeightedRedBlackTree <int, int> tree = new WeightedRedBlackTree <int, int>();
Assert.That(tree.Root, Is.Null);
// CopyTo should safely bail if the root is null.
WeightedRedBlackTreeNode <int, int>[] actualNodes = new WeightedRedBlackTreeNode <int, int> [0];
tree.CopyTo(actualNodes, 0);
int[] actualKeys = actualNodes.Select(n => n.Key).ToArray();
CollectionAssert.AreEqual(actualKeys, new int[0]);
}
{
WeightedRedBlackTree <int, int> tree = new WeightedRedBlackTree <int, int>
{
{ 1, 10 },
};
// The above is a valid red-black tree with only one node.
Assert.That(tree.Root.Key, Is.EqualTo(1));
// CopyTo performs an inorder walk using Next(), starting at
// Root's minimum subnode.
List <WeightedRedBlackTreeNode <int, int> > actualNodes = tree.ToList();
int[] actualKeys = actualNodes.Select(n => n.Key).ToArray();
CollectionAssert.AreEqual(actualKeys, new[] { 1 });
}
{
WeightedRedBlackTree <int, int> tree = new WeightedRedBlackTree <int, int>
{
{ 2, 20 },
{ 1, 10 },
};
// The above is a valid red-black tree in which the root is 2
// and it has a left child of 1. Let's check that to be sure...
Assert.That(tree.Root.Key, Is.EqualTo(2));
Assert.That(tree.Root.Left.Key, Is.EqualTo(1));
// CopyTo performs an inorder walk using Next(), starting at
// Root's minimum subnode. In this case, we ensure that
// Root is non-null and has a minimum subnode to start at.
List <WeightedRedBlackTreeNode <int, int> > actualNodes = tree.ToList();
int[] actualKeys = actualNodes.Select(n => n.Key).ToArray();
CollectionAssert.AreEqual(actualKeys, new[] { 1, 2 });
}
{
WeightedRedBlackTree <int, int> tree = new WeightedRedBlackTree <int, int>
{
{ 1, 10 },
{ 2, 20 },
};
// The above is a valid red-black tree in which the root is 1
// and it has a right child of 2. Let's check that to be sure...
Assert.That(tree.Root.Key, Is.EqualTo(1));
Assert.That(tree.Root.Right.Key, Is.EqualTo(2));
// CopyTo performs an inorder walk using Next(), starting at
// Root's minimum subnode. In this case, we ensure that
// Root is non-null but has no minimum subnode to start at.
List <WeightedRedBlackTreeNode <int, int> > actualNodes = tree.ToList();
int[] actualKeys = actualNodes.Select(n => n.Key).ToArray();
CollectionAssert.AreEqual(actualKeys, new[] { 1, 2 });
}
}
public void CannotRemoveKeysThatDontExist()
{
WeightedRedBlackTree <int, int> tree = new WeightedRedBlackTree <int, int>
{
{ 1, 10 },
{ 3, 20 },
{ 5, 30 },
{ 7, 40 },
{ 9, 50 },
};
Assert.That(tree.Remove(4), Is.False);
CollectionAssert.AreEqual(tree.KeyValuePairs, new[]
{
new KeyValuePair <int, int>(1, 10),
new KeyValuePair <int, int>(3, 20),
new KeyValuePair <int, int>(5, 30),
new KeyValuePair <int, int>(7, 40),
new KeyValuePair <int, int>(9, 50),
});
Assert.That(tree.Remove(3), Is.True);
CollectionAssert.AreEqual(tree.KeyValuePairs, new[]
{
new KeyValuePair <int, int>(1, 10),
new KeyValuePair <int, int>(5, 30),
new KeyValuePair <int, int>(7, 40),
new KeyValuePair <int, int>(9, 50),
});
Assert.That(tree.Remove(1), Is.True);
CollectionAssert.AreEqual(tree.KeyValuePairs, new[]
{
new KeyValuePair <int, int>(5, 30),
new KeyValuePair <int, int>(7, 40),
new KeyValuePair <int, int>(9, 50),
});
Assert.That(tree.Remove(7), Is.True);
CollectionAssert.AreEqual(tree.KeyValuePairs, new[]
{
new KeyValuePair <int, int>(5, 30),
new KeyValuePair <int, int>(9, 50),
});
Assert.That(tree.Remove(9), Is.True);
CollectionAssert.AreEqual(tree.KeyValuePairs, new[]
{
new KeyValuePair <int, int>(5, 30),
});
WeightedRedBlackTreeNode <int, int> fiveNode = tree.Find(5);
Assert.That(tree.Remove(5), Is.True);
tree.DeleteNode(null); // Make this is always a no-op.
CollectionAssert.AreEqual(tree.KeyValuePairs, new KeyValuePair <int, int> [0]);
Assert.That(tree.Remove(3), Is.False);
Assert.That(tree.Count, Is.Zero);
Assert.That(tree.Root, Is.Null);
tree.DeleteNode(fiveNode); // Make sure nothing bad happens with an empty tree.
}
