Atcoder Beginner Contest 324 G Generate Arrays 题解-Treap
为了更好的阅读体验，请点击这里
套上平衡树板子就能做的很快的题，然后因为是指针存树，因此交换只需要把序列大小较小的挨个拿出来插到相应的地方即可。复杂度 \(O(N \log^2 N)\)。
但是一定要记住 不可以直接使用 std::swap 交换包含带有指针的类的实例（如代码中的 Treap 类）！ 原因在于在 std::swap 函数中涉及了调用析构函数来析构用于承载交换的中间变量，如果你没写析构函数释放空间还好，如果写了那么它会把中间变量中的指针（从正常指针复制）指向的空间给释放掉！
为了避免这种情况，因此写一个成员函数用于交换。
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef double db;
typedef long double ld;
#define IL inline
#define fi first
#define se second
#define mk make_pair
#define pb push_back
#define SZ(x) (int)(x).size()
#define ALL(x) (x).begin(), (x).end()
#define dbg1(x) cout << #x << " = " << x << ", "
#define dbg2(x) cout << #x << " = " << x << endl
template <typename T>
void _debug(const char* format, T t) {
cerr << format << '=' << t << endl;
}
template <class First, class... Rest>
void _debug(const char* format, First first, Rest... rest) {
while (*format != ',') cerr << *format++;
cerr << '=' << first << ',';
_debug(format + 1, rest...);
}
template <typename T>
ostream& operator<<(ostream& os, const vector<T>& V) {
os << "[ ";
for (const auto& vv : V) os << vv << ", ";
os << ']';
return os;
}
#ifdef LOCAL
#define dbg(...) _debug(#__VA_ARGS__, __VA_ARGS__)
#else
#define dbg(...)
#endif
template<typename Tp> IL void read(Tp &x) {
x=0; int f=1; char ch=getchar();
while(!isdigit(ch)) {if(ch == '-') f=-1; ch=getchar();}
while(isdigit(ch)) { x=x*10+ch-'0'; ch=getchar();}
x *= f;
}
template<typename First, typename... Rest> IL void read(First &first, Rest&... rest) {
read(first); read(rest...);
}
int buf[42];
template<typename Tp> IL void write(Tp x) {
int p = 0;
if(x < 0) { putchar('-'); x=-x;}
if(x == 0) { putchar('0'); return;}
while(x) {
buf[++p] = x % 10;
x /= 10;
}
for(int i=p;i;i--) putchar('0' + buf[i]);
}
template<typename First, typename... Rest> IL void write(const First& first, const Rest&... rest) {
write(first); putchar(32); write(rest...);
}
template<class T> class Treap {
public:
Treap() {}
~Treap() { _clear(root);}
void insert(T x) { _insert(root, x);}
void erase(T x) { _erase(root, x);}
int rank(T x) { return _GetRankOfVal(root, x);}
T kth(int x) { assert(1 <= x && x <= root->sz); return _GetValOfRank(root, x);}
T pre(T x) { Node *ans = null; query_pre(root, x, ans); return ans->v;}
T nxt(T x) { Node *ans = null; query_nxt(root, x, ans); return ans->v;}
bool empty() { return root->sz == 0;}
int size() { return root -> sz;}
void clear() { _clear(root);}
void swap(Treap<T>& rhs) { std::swap(root, rhs.root);}
private:
struct Node {
Node *ch[2];
T v;
int sz, r, cnt;
Node() { sz = r = cnt = 0;}
Node(const T &v):v(v) { ch[0] = ch[1] = null; r=rand(); sz = cnt = 1;}
bool operator < (const Node& rhs) const { return r < rhs.r;}
int cmp(const T& x) const {
if(!(x < v || v < x)) return -1;
return v < x;
}
void upd() { sz = ch[0] -> sz + ch[1] -> sz + cnt;}
};
static Node *null;
Node *root = null;
void rotate(Node* &o, const int &d) {
Node *k = o->ch[d^1]; o->ch[d^1] = k->ch[d]; k->ch[d] = o;
o->upd(); k->upd(); o = k;
}
void _insert(Node* &o, const T &x) {
if (o == null) { o = new Node(x); return;}
o->sz++;
int d = o->cmp(x);
if (d == -1) {o->cnt++; return;}
_insert(o->ch[d], x);
if (o->r < o->ch[d]->r) rotate(o, d^1);
o -> upd();
}
void _erase(Node* &o, const T &x) {
if (o == null) return;
int d = o->cmp(x);
if (d == -1) {
Node* u = o;
if (o->cnt > 1) {o->cnt--; o->sz--; return;}
if (o->ch[0] != null && o->ch[1] != null) {
int d2 = o->ch[0]->r > o->ch[1]->r;
rotate(o, d2); _erase(o->ch[d2], x);
}
else {
if (o->ch[0] == null) o = o->ch[1]; else o = o->ch[0];
delete u;
}
}
else _erase(o->ch[d], x);
if(o != null) o->upd();
}
int _GetRankOfVal(Node *&o, const T &x) {
if (o == null) return 1;
if (!(o->v < x || x < o->v)) return o->ch[0]->sz + 1;
else if (o->v < x) return o->ch[0]->sz + o->cnt + _GetRankOfVal(o->ch[1], x);
else return _GetRankOfVal(o->ch[0], x);
}
T _GetValOfRank(Node *&o, const int &k) {
if (o == null) return T();
if (!(o->ch[0]->sz < k)) return _GetValOfRank(o->ch[0], k);
else if(o->ch[0]->sz + o->cnt < k)
return _GetValOfRank(o->ch[1], k - o->ch[0]->sz - o->cnt);
return o->v;
}
void query_pre(Node *&o, const T &x, Node *&ans) {
if (o == null) return;
if (o->v < x) { ans = o; query_pre(o->ch[1], x, ans);}
else query_pre(o->ch[0], x, ans);
}
void query_nxt(Node *&o, const T &x, Node *&ans) {
if (o == null) return;
if (x < o->v) { ans = o; query_nxt(o->ch[0], x, ans);}
else query_nxt(o->ch[1], x, ans);
}
void _clear(Node*& o) {
if (o == null || o == NULL) return;
_clear(o -> ch[0]);
_clear(o -> ch[1]);
delete o;
return;
}
};
template<class T> typename Treap<T>::Node* Treap<T>::null = new Node();
void solve() {
int n; read(n);
vector<int> a(n);
for (int i = 0; i < n; i++) read(a[i]);
int q; read(q);
vector<Treap<pair<int, int> > > id2val(q + 1), val2id(q + 1);
for (int i = 0; i < n; i++) id2val[0].insert(mk(i, a[i]));
for (int i = 0; i < n; i++) val2id[0].insert(mk(a[i], i));
for (int i = 1; i <= q; i++) {
int op, s, x; read(op, s, x);
vector<pair<int, int> > unsolved;
if (op == 1) {
int nowsz = id2val[s].size();
if (x >= nowsz / 2) { // 删后面的
for (int j = x + 1; j <= nowsz; j++) unsolved.push_back(id2val[s].kth(j));
}
else {
for (int j = 1; j <= x; j++) unsolved.push_back(id2val[s].kth(j));
}
for (auto v : unsolved) {
id2val[i].insert(v);
id2val[s].erase(v);
val2id[i].insert(mk(v.se, v.fi));
val2id[s].erase(mk(v.se, v.fi));
}
if (x < nowsz / 2) {
id2val[s].swap(id2val[i]);
val2id[s].swap(val2id[i]);
}
}
else {
int nowsz = val2id[s].size();
int rankx = val2id[s].rank(mk(x, (int)1e9)); // > x 第一个数的 rank
if (rankx >= nowsz / 2) { // 删后面的
for (int j = rankx; j <= nowsz; j++) unsolved.push_back(val2id[s].kth(j));
}
else {
for (int j = 1; j < rankx; j++) unsolved.push_back(val2id[s].kth(j));
}
for (auto v : unsolved) {
val2id[i].insert(v);
val2id[s].erase(v);
id2val[i].insert(mk(v.se, v.fi));
id2val[s].erase(mk(v.se, v.fi));
}
if (rankx < nowsz / 2) {
id2val[s].swap(id2val[i]);
val2id[s].swap(val2id[i]);
}
}
assert(id2val[i].size() == val2id[i].size());
write(id2val[i].size()); putchar(10);
}
}
int main() {
#ifdef LOCAL
freopen("test.in", "r", stdin);
// freopen("test.out", "w", stdout);
#endif
int T = 1;
// read(T);
while(T--) solve();
return 0;
}