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OI-codes/AcWing/253/253.cpp

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#include <cstdlib>
#include <iostream>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1e5 + 5;
int n, op, x;
// Treap
void insert(int);
void erase(int);
int getRank(int);
int getKth(int);
int main() {
std::ios::sync_with_stdio(false);
cin >> n;
while (n--) {
cin >> op >> x;
if (op == 1) {
insert(x);
} else if (op == 2) {
erase(x);
} else if (op == 3) {
cout << getRank(x) << endl;
} else if (op == 4) {
cout << getKth(x) << endl;
} else if (op == 5) {
cout << getKth(getRank(x) - 1) << endl;
} else {
cout << getKth(getRank(x + 1)) << endl;
}
}
return 0;
}
// === Treap ===
int root, cnt;
struct node {
int l, r, s, v, k;
node()
: l(0), r(0), s(0), v(0), k(rand()) {}
2022-05-20 01:23:27 +00:00
node(int _v)
: l(0), r(0), s(1), v(_v), k(rand()) {}
} tr[N];
inline void pushup(int u) {
tr[u].s = tr[tr[u].l].s + tr[tr[u].r].s + 1;
}
std::pair<int, int> split(int p, int k) {
if (!p) return std::make_pair(0, 0);
if (k <= tr[tr[p].l].s) {
auto o = split(tr[p].l, k);
tr[p].l = o.second;
pushup(p);
o.second = p;
return o;
}
auto o = split(tr[p].r, k - tr[tr[p].l].s - 1);
tr[p].r = o.first;
pushup(p);
o.first = p;
return o;
}
std::pair<int, int> splitByValue(int p, int v) {
if (!p) return std::make_pair(0, 0);
if (tr[p].v < v) {
auto o = splitByValue(tr[p].r, v);
tr[p].r = o.first;
pushup(p);
o.first = p;
return o;
}
auto o = splitByValue(tr[p].l, v);
tr[p].l = o.second;
pushup(p);
o.second = p;
return o;
}
int merge(int x, int y) {
if (!x || !y) return x | y;
if (tr[x].k > tr[y].k) {
tr[x].r = merge(tr[x].r, y);
pushup(x);
return x;
}
tr[y].l = merge(x, tr[y].l);
pushup(y);
return y;
}
void insert(int v) {
auto o = splitByValue(root, v);
int p = ++cnt;
tr[p] = node(v);
o.first = merge(o.first, p);
root = merge(o.first, o.second);
}
void erase(int v) {
auto o = splitByValue(root, v);
auto t = split(o.second, 1);
if (tr[t.first].v == v) {
root = merge(o.first, t.second);
} else {
root = merge(o.first, merge(t.first, t.second));
}
}
int getRank(int v) {
auto o = splitByValue(root, v);
int r = tr[o.first].s + 1;
root = merge(o.first, o.second);
return r;
}
int getKth(int k) {
auto x = split(root, k - 1);
auto y = split(x.second, 1);
int r = y.first;
root = merge(x.first, merge(y.first, y.second));
return tr[r].v;
}