public void MergeAndCountInversionsWorksWellOnPartialRight()
{
var solver = new FindArrayInversionsCount();
var sortedArray = new int[4];
Assert.AreEqual(0ul, solver.MergeAndCountInversions(
new[] { 1, 2, 3, 4 },
0, 3,
3, 1,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 2, 3, 4 }, sortedArray);
Assert.AreEqual(1ul, solver.MergeAndCountInversions(
new[] { 1, 2, 20, 8 },
0, 3,
3, 1,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 2, 8, 20 }, sortedArray);
sortedArray = new int[5];
Assert.AreEqual(4ul, solver.MergeAndCountInversions(
new[] { 1, 19, 20, 8, 9 },
0, 3,
3, 2,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 8, 9, 19, 20 }, sortedArray);
}
public void CanFindInversionsForLargeRandom()
{
var solver = new FindArrayInversionsCount();
var array = Enumerable.Range(0, 1000).ToArray();
array.Shuffle();
Assert.AreEqual(solver.CalcInversionsCountBrute(array), solver.CalcInversionsCount(array));
}
public void CanFindInversionsCount()
{
var solver = new FindArrayInversionsCount();
Assert.AreEqual(1ul, solver.CalcInversionsCount(new[] { 6, 5 }));
Assert.AreEqual(3ul, solver.CalcInversionsCount(new[] { 6, 5, 4 }));
Assert.AreEqual(6ul, solver.CalcInversionsCount(new[] { 6, 5, 4, 3 }));
Assert.AreEqual(15ul, solver.CalcInversionsCount(new[] { 6, 5, 4, 3, 2, 1 }));
Assert.AreEqual(6ul, solver.CalcInversionsCount(new[] { 1, 2, 6, 5, 4, 3 }));
Assert.AreEqual(6ul, solver.CalcInversionsCount(new[] { 1, 2, 6, 0, 5, 4, 18 }));
Assert.AreEqual(66ul, solver.CalcInversionsCount(new[] { 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 }));
}
public void MergeAndCountInversionsWorksWellTrivial()
{
var solver = new FindArrayInversionsCount();
var sortedArray = new int[2];
Assert.AreEqual(0ul, solver.MergeAndCountInversions(
new[] { 1, 2 },
0, 1,
1, 1,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 2 }, sortedArray);
Assert.AreEqual(1ul, solver.MergeAndCountInversions(
new[] { 2, 1 },
0, 1,
1, 1,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 2 }, sortedArray);
}
public void CanFindInversionsForRandom()
{
var solver = new FindArrayInversionsCount();
for (var size = 2; size < 100; size++)
{
var array = Enumerable.Range(1, size).ToArray();
array.Shuffle();
Console.WriteLine(size);
var expected = solver.CalcInversionsCountBrute(array);
var actual = solver.CalcInversionsCount(array.ToArray());
if (expected != actual)
{
Console.WriteLine(", ".Join(array));
}
Assert.AreEqual(expected, actual);
}
}
public void MergeAndCountInversionsWorksWell6()
{
var solver = new FindArrayInversionsCount();
var sortedArray = new int[6];
Assert.AreEqual(0ul, solver.MergeAndCountInversions(
new[] { 1, 2, 3, 4, 5, 6 },
0, 3,
3, 3,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 2, 3, 4, 5, 6 }, sortedArray);
Assert.AreEqual(3ul, solver.MergeAndCountInversions(
new[] { 1, 2, 20, 8, 9, 10 },
0, 3,
3, 3,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 2, 8, 9, 10, 20 }, sortedArray);
Assert.AreEqual(6ul, solver.MergeAndCountInversions(
new[] { 1, 19, 20, 8, 9, 10 },
0, 3,
3, 3,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 8, 9, 10, 19, 20 }, sortedArray);
Assert.AreEqual(5ul, solver.MergeAndCountInversions(
new[] { 1, 15, 20, 8, 9, 17 },
0, 3,
3, 3,
sortedArray,
0));
AssertHelper.Seq(new[] { 1, 8, 9, 15, 17, 20 }, sortedArray);
}
