public IntermediateResult CountAndSort(long[] input)
{
var result = new IntermediateResult();
//trivial case
if (input.Length <= 1)
{
result.Count = 0;
result.IntermediateArray = input;
}
else
{
var parts = Split(input);
var leftResult = CountAndSort(parts.Item1);
var rightResult = CountAndSort(parts.Item2);
var split = CountSplitInv(leftResult.IntermediateArray, rightResult.IntermediateArray);
result.Count = leftResult.Count + rightResult.Count + split.Count;
result.IntermediateArray = split.IntermediateArray;
}
return result;
}
public IntermediateResult CountSplitInv(long[] left, long[] right)
{
var result = new IntermediateResult();
result.IntermediateArray = new long[left.Length + right.Length];
var resArr = result.IntermediateArray;
var i = 0;
var j = 0;
for (int k = 0; k < resArr.Length; k++)
{
if (i == left.Length)
{
resArr[k] = right[j];
j++;
continue;
}
if (j == right.Length)
{
resArr[k] = left[i];
i++;
continue;
}
if (left[i] <= right[j])
{
resArr[k] = left[i];
i++;
}
else
{
resArr[k] = right[j];
result.Count += left.Length - i;
j++;
}
}
return result;
}