Atcoder Beginner Contest 324 G Generate Arrays 题解-Treap

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题目链接

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;
}