public int Solve()
{
var bitree = new BITree(n + 1);
int[] pos = new int[n + 1];
for (int i = 0; i < n; i++)
{
var x = ns[i];
pos[x] = i + 1;
}
int ans = 0;
for (int i = 1; i <= n; i++)
{
int s = bitree.Sum(pos[i], n);
if (s > MAX_BRIBING_NUM)
{
return(-1);
}
bitree.Add(pos[i], 1);
ans += s;
}
return(ans);
}
public static int GetInversionNumber(string input)
{
List <NumberNode> numberList = new List <NumberNode>(input.Length);
//离散化过程
for (int i = 0, length = input.Length; i < length; ++i)
{
numberList.Add(new NumberNode()
{
value = int.Parse(input[i].ToString()),
order = i
});
}
numberList.Sort(((node1, node2) =>
{
return(node1.value.CompareTo(node2.value));
}));
int[] values = new int[input.Length];
for (int i = 0, count = numberList.Count; i < count; ++i)
{
values[numberList[i].order] = i + 1;
}
//树状数组处理过程
BITree biTree = new BITree(input.Length);
int inversionNum = 0;
for (int i = 0, length = values.Length; i < length; ++i)
{
biTree.Add(values[i], 1);
inversionNum += i + 1 - biTree.Sum(values[i]);
}
return(inversionNum);
}
