Luogu3850 [TJOI2007]书架 （平衡树）

将要插入位置前和前前splay，再连在右子树上。

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
#define R(a,b,c) for(register int  a = (b); a <= (c); ++ a)
#define nR(a,b,c) for(register int  a = (b); a >= (c); -- a)
#define Max(a,b) ((a) > (b) ? (a) : (b))
#define Min(a,b) ((a) < (b) ? (a) : (b))
#define Fill(a,b) memset(a, b, sizeof(a))
#define Abs(a) ((a) < 0 ? -(a) : (a))
#define Swap(a,b) a^=b^=a^=b
#define ll long long
#define ON_DEBUG
#ifdef ON_DEBUG
#define D_e_Line printf("\n\n----------\n\n")
#define D_e(x)  cout << #x << " = " << x << endl
#define Pause() system("pause")
#define FileOpen() freopen("in.txt","r",stdin);
#else
#define D_e_Line ;
#define D_e(x)  ;
#define Pause() ;
#define FileOpen() ;
#endif
struct ios{
    template<typename ATP>ios& operator >> (ATP &x){
        x = 0; int f = 1; char c;
        for(c = getchar(); c < '0' || c > '9'; c = getchar()) if(c == '-')  f = -1;
        while(c >= '0' && c <= '9') x = x * 10 + (c ^ '0'), c = getchar();
        x*= f;
        return *this;
    }
}io;
using namespace std;
const int N = 1000007;
struct Tree{
	int ch[2], fa, val, siz;
}t[N];
int treeIndex,root;
inline void Pushup(int rt){
	t[rt].siz = t[t[rt].ch[0]].siz + t[t[rt].ch[1]].siz + 1;
}
inline int Ident(int rt){
	return t[t[rt].fa].ch[1] == rt;
}
inline void Rotate(int x){
	int y = t[x].fa, z = t[y].fa, k = Ident(x);
	t[z].ch[Ident(y)] = x, t[x].fa = z;
	t[y].ch[k] = t[x].ch[k ^ 1], t[t[x].ch[k ^ 1]].fa = y;
	t[x].ch[k ^ 1] = y, t[y].fa = x;
	Pushup(y), Pushup(x);
}
inline void Splay(int x, int pos){
	while(t[x].fa != pos){
		int y = t[x].fa, z = t[y].fa;
		if(z != pos){
			Ident(x) == Ident(y) ? Rotate(y) : Rotate(x);
		}
		Rotate(x);
	}
	if(!pos) root = x;
}
inline void Insert(int x){
	int u = root, fa = 0;
	while(u && t[u].val != x){
		fa = u;
		u = t[u].ch[x > t[u].val];
	}
	if(u){
		return;
	}
	else{
		u = ++treeIndex;
		t[u].ch[0] = t[u].ch[1] = 0;
		t[u].val = x;
		t[u].fa = fa;
		t[u].siz = 1;
		if(fa) t[fa].ch[x > t[fa].val] = u;
	}
	Splay(u, 0);
}
inline int Kth(int k){
	int u = root;
	while(1){
		int v = t[u].ch[0];
		if(t[v].siz + 1 < k){
			k -= t[v].siz + 1;
			u = t[u].ch[1];
		}
		else if(v && t[v].siz >= k){ // !
			u = v;
		}
		else
			return u; // !
	}
}
char book[N][17];
int main(){
//FileOpen();
	Insert(2147483647);
	Insert(-2147483647);
	int n;
    io >> n;
    R(i,1,n){
        scanf("%s", book[i]);
        Insert(i);
    }
    int m;
	io >> m;
    R(i,1,m){
        scanf("%s", book[n+i]);
        int x;
        io >> x;
        int nxtNxt=Kth(x + 2);
        Splay(nxtNxt, 0);
        int nxt=Kth(x + 1);
        Splay(nxt, nxtNxt);
        int u = ++treeIndex;
        t[nxt].ch[1] = u;
        t[u].ch[0] = t[u].ch[1] = 0;
        t[u].fa = nxt;
        t[u].val = x + 2;
        t[u].siz = 1;
        Pushup(nxt), Pushup(nxtNxt);
    }
    int Ques;
    io >> Ques;
    while(Ques--){
        int x;
		io >> x;
        printf("%s\n", book[Kth(x + 2) - 2]);
    }
    return 0;
}