Size Balanced Tree

论文足足看了两天，这是成果：

#include <cstdio>

const int maxn = 1000000;

int n, a, b, c, root;
int Child[maxn][2];
int Key[maxn], Size[maxn], Count;

int New_node (int v)
{
    Count++;
    Key[Count] = v;
    Size[Count] = 1;
    return Count;
}

void Rotate (int& x, int d)
{
    int k = Child[x][!d];
    Child[x][!d] = Child[k][d];
    Child[k][d] = x;
    Size[k] = Size[x];
    Size[x] = Size[Child[x][0]] + Size[Child[x][1]] + 1;
    x = k;
}

void Maintain (int& t, int d)
{
    if (!t) return;
    if (Size[Child[Child[t][d]][d]] > Size[Child[t][!d]])
        Rotate (t, !d);
    else if (Size[Child[Child[t][d]][!d]] > Size[Child[t][!d]])
        Rotate (Child[t][d], d), Rotate (t, !d);
    else return;
    Maintain (Child[t][0], 0);
    Maintain (Child[t][1], 1);
    Maintain (t, 0);
    Maintain (t, 1);
}

void Insert (int& t, int v)
{
    if (t == 0) t = New_node (v);
    else
    {
        Size[t]++;
        Insert (Child[t][v >= Key[t]], v);
        Maintain (t, v >= Key[t]);
    }
}

int Delete (int& t, int v)
{
    int Ret;
    Size[t]--;
    if (v == Key[t] || Child[t][v > Key[t]] == 0)
    {
        Ret = Key[t];
        if (Child[t][0] && Child[t][1])
            Key[t] = Delete (Child[t][0], v + 1);
        else t = Child[t][0] + Child[t][1];
    }else
        Ret = Delete (Child[t][v > Key[t]], v);
    return Ret;
}

int Rank (int t, int v)
{
    if (t == 0) return 1;
    if (v <= Key[t]) return Rank (Child[t][0], v);
    return Rank (Child[t][1], v) + Size[Child[t][0]] + 1;
}

int Select (int t, int k)
{
    if (Child[t][0] && Size[Child[t][0]] >= k)
        return Select (Child[t][0], k);
    if (Size[Child[t][0]] + 1 == k) return Key[t];
    return Select (Child[t][1], k - Size[Child[t][0]] - 1);
}

void Print (int t)
{
    if (t == 0) return;
    Print (Child[t][0]);
    printf ("%d ", Key[t]);
    Print (Child[t][1]);
}

int main ()
{
    scanf ("%d", &n);
    for (int i = 0; i < n; i++)
    {
        scanf ("%d %d", &a, &b);
        if (a == 1) Insert (root, b);
        if (a == 2)
        {
            c = Delete (root, b);
            if (c != b) Insert (root, c);
        }
        if (a == 3) printf ("%d
", Select (root, b));
        if (a == 4) printf ("%d
", Rank (root, b));
        if (a == 5)
        {
            if (b == 1)
            {
                for (int j = 1; j <= Count; j++)
                    printf ("Child : %d %d, Key : %d
", Child[j][0], Child[j][1], Key[j]);
            }else Print (root), printf ("
");
        }
    }
}