public void BTree_AccuracyTest()
{
var nodeCount = 1000;
var rnd = new Random();
var randomNumbers = Enumerable.Range(1, nodeCount)
.OrderBy(x => rnd.Next())
.ToList();
var order = 5;
var tree = new BTree <int>(order);
for (int i = 0; i < nodeCount; i++)
{
tree.Insert(randomNumbers[i]);
var actualMaxHeight = BTreeTester.GetMaxHeight(tree.Root);
var actualMinHeight = BTreeTester.GetMinHeight(tree.Root);
Assert.IsTrue(actualMaxHeight == actualMinHeight);
//https://en.wikipedia.org/wiki/B-tree#Best_case_and_worst_case_heights
var theoreticalMaxHeight = Math.Ceiling(Math.Log((i + 2) / 2, (int)Math.Ceiling((double)order / 2)));
Assert.IsTrue(actualMaxHeight <= theoreticalMaxHeight);
Assert.IsTrue(tree.Count == i + 1);
Assert.IsTrue(tree.HasItem(randomNumbers[i]));
}
for (int i = 0; i < nodeCount; i++)
{
Assert.IsTrue(tree.HasItem(randomNumbers[i]));
}
Assert.AreEqual(tree.Max, randomNumbers.Max());
Assert.AreEqual(tree.Min, randomNumbers.Min());
//shuffle again before deletion tests
randomNumbers = Enumerable.Range(1, nodeCount)
.OrderBy(x => rnd.Next())
.ToList();
for (int i = 0; i < nodeCount; i++)
{
tree.Delete(randomNumbers[i]);
Assert.IsFalse(tree.HasItem(randomNumbers[i]));
var actualMaxHeight = BTreeTester.GetMaxHeight(tree.Root);
var actualMinHeight = BTreeTester.GetMinHeight(tree.Root);
Assert.IsTrue(actualMaxHeight == actualMinHeight);
//https://en.wikipedia.org/wiki/B-tree#Best_case_and_worst_case_heights
var theoreticalMaxHeight = Math.Ceiling(Math.Log((nodeCount - i + 2) / 2, (int)Math.Ceiling((double)order / 2)));
Assert.IsTrue(actualMaxHeight <= theoreticalMaxHeight);
Assert.IsTrue(tree.Count == nodeCount - 1 - i);
}
Assert.IsTrue(tree.Count == 0);
}
public void BPTree_AccuracyTest()
{
var nodeCount = 1000;
var rnd = new Random();
var randomNumbers = Enumerable.Range(1, nodeCount)
.OrderBy(x => rnd.Next())
.ToList();
var order = 5;
var tree = new BPTree <int>(order);
for (int i = 0; i < nodeCount; i++)
{
tree.Insert(randomNumbers[i]);
var actualMaxHeight = BTreeTester.GetMaxHeight(tree.Root);
var actualMinHeight = BTreeTester.GetMinHeight(tree.Root);
Assert.IsTrue(actualMaxHeight == actualMinHeight);
//https://en.wikipedia.org/wiki/B-tree#Best_case_and_worst_case_heights
var theoreticalMaxHeight = Math.Ceiling(Math.Log((i + 2) / 2, (int)Math.Ceiling((double)order / 2))) + 1;
Assert.IsTrue(actualMaxHeight <= theoreticalMaxHeight);
Assert.IsTrue(tree.Count == i + 1);
Assert.IsTrue(tree.HasItem(randomNumbers[i]));
}
for (int i = 0; i < nodeCount; i++)
{
Assert.IsTrue(tree.HasItem(randomNumbers[i]));
}
Assert.AreEqual(tree.Max, randomNumbers.Max());
Assert.AreEqual(tree.Min, randomNumbers.Min());
//check that the elements are in sorted order
//since B+ tree stores all elements in leaves in sorted order from left to right
int j = 1;
foreach (var element in tree)
{
Assert.AreEqual(j, element);
j++;
}
//shuffle again before deletion tests
randomNumbers = Enumerable.Range(1, nodeCount)
.OrderBy(x => rnd.Next())
.ToList();
for (int i = 0; i < nodeCount; i++)
{
tree.Delete(randomNumbers[i]);
Assert.IsFalse(tree.HasItem(randomNumbers[i]));
var actualMaxHeight = BTreeTester.GetMaxHeight(tree.Root);
var actualMinHeight = BTreeTester.GetMinHeight(tree.Root);
Assert.IsTrue(actualMaxHeight == actualMinHeight);
//https://en.wikipedia.org/wiki/B-tree#Best_case_and_worst_case_heights
var theoreticalMaxHeight = i == nodeCount - 1 ? 0 : Math.Ceiling(Math.Log((nodeCount - i - 1 + 1) / 2, (int)Math.Ceiling((double)order / 2))) + 1;
Assert.IsTrue(actualMaxHeight <= theoreticalMaxHeight);
Assert.IsTrue(tree.Count == nodeCount - 1 - i);
}
Assert.IsTrue(BTreeTester.GetMaxHeight(tree.Root) == 0);
Assert.IsTrue(tree.Count == 0);
}