Splay模板

#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
int rt, tot, fa[N], ch[N][2], val[N], cnt[N], sz[N];
void maintain(int x) { sz[x] = sz[ch[x][0]] + sz[ch[x][1]] + cnt[x]; }
bool get(int x) { return x == ch[fa[x]][1]; }
void clear(int x) {
ch[x][0] = ch[x][1] = fa[x] = val[x] = sz[x] = cnt[x] = 0;
}
void rotate(int x) {
int y = fa[x], z = fa[y], chk = get(x);
ch[y][chk] = ch[x][chk ^ 1];
fa[ch[x][chk ^ 1]] = y;
ch[x][chk ^ 1] = y;
fa[y] = x;
fa[x] = z;
if (z) ch[z][y == ch[z][1]] = x;
maintain(x);
maintain(y);
}
void splay(int x) {
for (int f = fa[x]; f = fa[x], f; rotate(x))
    if (fa[f]) rotate(get(x) == get(f) ? f : x);
rt = x;
}
void ins(int k) {
if (!rt) {
    val[++tot] = k;
    cnt[tot]++;
    rt = tot;
    maintain(rt);
    return;
}
int cnr = rt, f = 0;
while (1) {
    if (val[cnr] == k) {
    cnt[cnr]++;
    maintain(cnr);
    maintain(f);
    splay(cnr);
    break;
    }
    f = cnr;
    cnr = ch[cnr][val[cnr] < k];
    if (!cnr) {
    val[++tot] = k;
    cnt[tot]++;
    fa[tot] = f;
    ch[f][val[f] < k] = tot;
    maintain(tot);
    maintain(f);
    splay(tot);
    break;
    }
}
}
int rk(int k) {
int res = 0, cnr = rt;
while (1) {
    if (k < val[cnr]) {
    cnr = ch[cnr][0];
    } else {
    res += sz[ch[cnr][0]];
    if (k == val[cnr]) {
        splay(cnr);
        return res + 1;
    }
    res += cnt[cnr];
    cnr = ch[cnr][1];
    }
}
}
int kth(int k) {
int cnr = rt;
while (1) {
    if (ch[cnr][0] && k <= sz[ch[cnr][0]]) {
    cnr = ch[cnr][0];
    } else {
    k -= cnt[cnr] + sz[ch[cnr][0]];
    if (k <= 0) {
        splay(cnr);
        return val[cnr];
    }
    cnr = ch[cnr][1];
    }
}
}
int pre() {
int cnr = ch[rt][0];
while (ch[cnr][1]) cnr = ch[cnr][1];
splay(cnr);
return cnr;
}
int nxt() {
int cnr = ch[rt][1];
while (ch[cnr][0]) cnr = ch[cnr][0];
splay(cnr);
return cnr;
}
void del(int k) {
rk(k);
if (cnt[rt] > 1) {
    cnt[rt]--;
    maintain(rt);
    return;
}
if (!ch[rt][0] && !ch[rt][1]) {
    clear(rt);
    rt = 0;
    return;
}
if (!ch[rt][0]) {
    int cnr = rt;
    rt = ch[rt][1];
    fa[rt] = 0;
    clear(cnr);
    return;
}
if (!ch[rt][1]) {
    int cnr = rt;
    rt = ch[rt][0];
    fa[rt] = 0;
    clear(cnr);
    return;
}
int cnr = rt;
int x = pre();
splay(x);
fa[ch[cnr][1]] = x;
ch[x][1] = ch[cnr][1];
clear(cnr);
maintain(rt);
}
int main() {
  int n, opt, x;
  for (scanf("%d", &n); n; --n) {
    scanf("%d%d", &opt, &x);
    if (opt == 1)
      ins(x);
    else if (opt == 2)
      del(x);
    else if (opt == 3)
      printf("%d\n", rk(x));
    else if (opt == 4)
      printf("%d\n", kth(x));
    else if (opt == 5)
      ins(x), printf("%d\n", val[pre()]), del(x);
    else
      ins(x), printf("%d\n", val[nxt()]), del(x);
  }
  return 0;
}