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Treap.cpp
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148 lines (148 loc) · 3.04 KB
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// https://www.luogu.com.cn/problem/P3369
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
#define IOS \
ios::sync_with_stdio(0); \
cin.tie(0); \
cout.tie(0)
#define rep(i, j, k) for (int i = j; i <= k; ++i)
#define rrep(i, j, k) for (int i = j; i >= k; --i)
#define clr(a, b) memset(a, b, sizeof(a))
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
const double EPS = 1e-8;
const int N = 1e5 + 5;
int tn;
int root;
int key[N];
int prior[N];
int ls[N];
int rs[N];
int cnt[N];
int siz[N];
mt19937 rd(random_device{}());
void upd(int p) { siz[p] = siz[ls[p]] + siz[rs[p]] + cnt[p]; }
int lrot(int p) {
int r = rs[p];
rs[p] = ls[r];
ls[r] = p;
upd(p);
upd(r);
return r;
}
int rrot(int p) {
int l = ls[p];
ls[p] = rs[l];
rs[l] = p;
upd(p);
upd(l);
return l;
}
int add(int p, int x, int pr) {
if (!p) {
key[++tn] = x;
prior[tn] = pr;
cnt[tn] = 1;
siz[tn] = 1;
return tn;
}
if (x == key[p]) {
++cnt[p];
} else if (x < key[p]) {
ls[p] = add(ls[p], x, pr);
if (prior[ls[p]] > prior[p]) {
p = rrot(p);
}
} else {
rs[p] = add(rs[p], x, pr);
if (prior[rs[p]] > prior[p]) {
p = lrot(p);
}
}
upd(p);
return p;
}
int del(int p, int x) {
if (!p) return 0;
if (x == key[p]) {
if (cnt[p] > 1) {
--cnt[p];
} else {
if (!ls[p] && !rs[p]) {
return 0;
} else if (!ls[p] && rs[p]) {
return rs[p];
} else if (ls[p] && !rs[p]) {
return ls[p];
} else {
if (prior[ls[p]] > prior[rs[p]]) {
p = rrot(p);
rs[p] = del(rs[p], x);
} else {
p = lrot(p);
ls[p] = del(ls[p], x);
}
}
}
} else if (x < key[p]) {
ls[p] = del(ls[p], x);
} else {
rs[p] = del(rs[p], x);
}
upd(p);
return p;
}
int get_rank(int p, int x) {
if (!p) return 1;
if (key[p] >= x) return get_rank(ls[p], x);
if (key[p] < x) return siz[ls[p]] + cnt[p] + get_rank(rs[p], x);
}
int get_key(int p, int x) {
if (siz[ls[p]] >= x) return get_key(ls[p], x);
if (siz[ls[p]] + cnt[p] < x) return get_key(rs[p], x - siz[ls[p]] - cnt[p]);
return key[p];
}
int get_pre(int p, int x) { return get_key(root, get_rank(root, x) - 1); }
int get_post(int p, int x) { return get_key(root, get_rank(root, x + 1)); }
inline void solve() {
tn = 0;
root = 0;
clr(key, 0);
clr(prior, 0);
clr(ls, 0);
clr(rs, 0);
clr(cnt, 0);
clr(siz, 0);
int m;
scanf("%d", &m);
int op, x;
while (m--) {
scanf("%d%d", &op, &x);
if (op == 1) {
root = add(root, x, rd());
} else if (op == 2) {
root = del(root, x);
} else if (op == 3) {
printf("%d\n", get_rank(root, x));
} else if (op == 4) {
printf("%d\n", get_key(root, x));
} else if (op == 5) {
printf("%d\n", get_pre(root, x));
} else {
printf("%d\n", get_post(root, x));
}
}
}
inline void init() {}
int main() {
IOS;
init();
int t = 1;
while (t--) {
solve();
}
return 0;
}