public void Modify(int index, int difference)
{
index += 1; // offset
while (index < tree.Length)
{
tree[index] += difference;
index += BitManipulation.GetFirstBit(index);
}
}
public int GetCumulative(int right)
{
right += 1; // offset
int sum = 0;
while (right > 0)
{
sum += tree[right];
right = right - BitManipulation.GetFirstBit(right);
}
return(sum);
}