public static long C(long n)
{
long result = 0;
var points = PointFactory.P(n).OrderBy(point => point.A).ToList();
var invIndexes = new InvIndex[points.Count];
Parallel.For(0, points.Count, i =>
{
var max = GetInverseIndex(points, i, false);
var min = (max - 1) % points.Count;
invIndexes[i] = new InvIndex(min, max);
});
invIndexes = invIndexes.OrderBy(i => i.Min).ToArray();
long lastSum = 0;
for (var i = 1; i < invIndexes.Count(); i++)
{
lastSum += invIndexes[i].Min - invIndexes[0].Max + 1;
}
var totalSum = lastSum;
for (var i = 1; i < invIndexes.Count(); i++)
{
if (invIndexes[i].Min == invIndexes[i - 1].Min && invIndexes[i].Max == invIndexes[i - 1].Max)
{
continue;
}
lastSum -= (invIndexes[i].Min - invIndexes[i - 1].Max + 1) * (invIndexes.Count() - i);
totalSum += lastSum;
}
return(totalSum);
//for (var i = 0; i < points.Count; i++)
//{
// for (var j = i + 1; j < points.Count; j++)
// {
// result += invIndexes[j].Min > invIndexes[i].Max
// ? invIndexes[j].Min - invIndexes[i].Max
// : invIndexes[j].Min + points.Count - invIndexes[i].Max;
// }
//}
//return result;
}
public static long C(long n)
{
long result = 0;
var points = PointFactory.P(n).OrderBy(point => point.A).ToList();
var invIndexes = new InvIndex[points.Count];
Parallel.For(0, points.Count, i =>
{
var max = GetInverseIndex(points, i, false);
var min = (max - 1)%points.Count;
invIndexes[i] = new InvIndex(min, max);
});
invIndexes = invIndexes.OrderBy(i => i.Min).ToArray();
long lastSum = 0;
for (var i = 1; i < invIndexes.Count(); i++)
{
lastSum += invIndexes[i].Min - invIndexes[0].Max + 1;
}
var totalSum = lastSum;
for (var i = 1; i < invIndexes.Count(); i++)
{
if (invIndexes[i].Min == invIndexes[i - 1].Min && invIndexes[i].Max == invIndexes[i - 1].Max)
{
continue;
}
lastSum -= (invIndexes[i].Min - invIndexes[i - 1].Max + 1)* (invIndexes.Count() - i);
totalSum += lastSum;
}
return totalSum;
//for (var i = 0; i < points.Count; i++)
//{
// for (var j = i + 1; j < points.Count; j++)
// {
// result += invIndexes[j].Min > invIndexes[i].Max
// ? invIndexes[j].Min - invIndexes[i].Max
// : invIndexes[j].Min + points.Count - invIndexes[i].Max;
// }
//}
//return result;
}
