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OI-codes/S2OJ/99/99.cpp

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#include <cstdlib>
#include <iostream>
using std::cin;
using std::cout;
#define endl '\n'
const int N = 100005;
class Treap {
private:
int root, cnt;
struct node {
int l, r, s, v, k;
node();
node(int);
} tr[N];
void pushup(int);
std::pair<int, int> split(int, int);
std::pair<int, int> splitByValue(int, int);
int merge(int, int);
int find(int, int);
public:
void insert(int);
void erase(int);
int getRank(int);
int getKth(int);
} tree;
int n, op, x;
int main() {
std::ios::sync_with_stdio(false);
cin >> n;
while (n--) {
cin >> op >> x;
if (op == 1) {
tree.insert(x);
} else if (op == 2) {
tree.erase(x);
} else if (op == 3) {
cout << tree.getRank(x) << endl;
} else if (op == 4) {
cout << tree.getKth(x) << endl;
} else if (op == 5) {
cout << tree.getKth(tree.getRank(x) - 1) << endl;
} else {
cout << tree.getKth(tree.getRank(x + 1)) << endl;
}
}
return 0;
}
// === Treap ===
// struct Treap::node
Treap::node::node()
: l(0), r(0), s(0), v(0), k(rand()) {}
Treap::node::node(int _v)
: l(0), r(0), s(1), v(_v), k(rand()) {}
// class Treap
inline void Treap::pushup(int u) {
this->tr[u].s = this->tr[this->tr[u].l].s + this->tr[this->tr[u].r].s + 1;
}
std::pair<int, int> Treap::split(int p, int k) {
if (!p) return std::make_pair(0, 0);
if (k <= this->tr[this->tr[p].l].s) {
auto o = this->split(this->tr[p].l, k);
this->tr[p].l = o.second;
this->pushup(p);
o.second = p;
return o;
}
auto o = this->split(this->tr[p].r, k - this->tr[this->tr[p].l].s - 1);
this->tr[p].r = o.first;
this->pushup(p);
o.first = p;
return o;
}
std::pair<int, int> Treap::splitByValue(int p, int v) {
if (!p) return std::make_pair(0, 0);
if (this->tr[p].v < v) {
auto o = this->splitByValue(tr[p].r, v);
this->tr[p].r = o.first;
this->pushup(p);
o.first = p;
return o;
}
auto o = splitByValue(this->tr[p].l, v);
this->tr[p].l = o.second;
this->pushup(p);
o.second = p;
return o;
}
int Treap::merge(int x, int y) {
if (!x) return y;
if (!y) return x;
if (this->tr[x].k > this->tr[y].k) {
this->tr[x].r = merge(this->tr[x].r, y);
this->pushup(x);
return x;
}
this->tr[y].l = merge(x, this->tr[y].l);
this->pushup(y);
return y;
}
int Treap::find(int p, int v) {
if (!p) return 0;
if (this->tr[p].v == v) return p;
if (this->tr[p].v > v) return this->find(this->tr[p].l, v);
return this->find(this->tr[p].r, v);
}
void Treap::insert(int v) {
auto o = this->splitByValue(root, v);
int p = ++this->cnt;
this->tr[p] = Treap::node(v);
o.first = this->merge(o.first, p);
this->root = this->merge(o.first, o.second);
}
void Treap::erase(int v) {
auto o = this->splitByValue(root, v);
auto t = o;
if (this->find(o.second, v)) {
t = this->split(o.second, 1);
}
this->root = this->merge(o.first, t.second);
}
inline int Treap::getRank(int v) {
auto x = this->splitByValue(this->root, v);
int r = this->tr[x.first].s;
this->root = merge(x.first, x.second);
return ++r;
}
int Treap::getKth(int k) {
auto x = this->split(this->root, k - 1);
auto y = this->split(x.second, 1);
int o = y.first;
this->root = this->merge(x.first, this->merge(y.first, y.second));
return tr[o].v;
}