BZOJ3224

http://www.lydsy.com/JudgeOnline/problem.php?id=3224

由于平衡树不太会写，就写棵线段树凑合着
就开棵值域线段树，
添加/删除，就是在包含改数的区间节点+1/-1
询问某数的排名时，就是经过右节点时，把左边子树的值加上
询问某排名的数时，就是类似求kth时的操作
询问某数前驱后继时，询问某数排名，在对该排名进行访问kth

#include<cstdio>
#include<algorithm>
#define FOR(i,s,t) for(register int i=s;i<=t;++i)
#define ls k<<1,l,mid
#define rs k<<1|1,mid+1,r
#define gc getchar()
using namespace std;
const int N=400011;
int n,p;
int a[N],b[N],c[N];
namespace Segment_Tree{
	int tr[N];
	inline void modify(int x,int v,int k=1,int l=1,int r=c[0]){
		tr[k]+=v;
		if(l==r)return ;
		int mid=(l+r)>>1;
		x<=mid?modify(x,v,ls):modify(x,v,rs);
	}
	inline int query_num(int x,int k=1,int l=1,int r=c[0]){
		if(l==r)return l;
		int mid=(l+r)>>1;
		return x<=tr[k<<1]?query_num(x,ls):query_num(x-tr[k<<1],rs);
	}
	inline int query_pos(int x,int type,int k=1,int l=1,int r=c[0]){
		if(l==r){
			if(type==3)return 1;
			if(type==5)return 0;
			if(type==6)return tr[k]+1;
		}
		int mid=(l+r)>>1;
		return x<=mid?query_pos(x,type,ls):(tr[k<<1]+query_pos(x,type,rs));
	}
}
using namespace Segment_Tree;
inline void disc_init(){
	sort(c+1,c+c[0]+1);
	c[0]=unique(c+1,c+c[0]+1)-c-1;
	FOR(i,1,n)
		if(a[i]!=4)b[i]=lower_bound(c+1,c+c[0]+1,b[i])-c;
}
inline int read(){
	char c;while(c=gc,c==' '||c=='\n');int data=0,f=1;
	c=='-'?f=-1:data=c-48;
	while(c=gc,c>='0'&&c<='9')data=(data<<1)+(data<<3)+c-48;
	return data*f;
}
int main(){
	n=read();
	FOR(i,1,n){
		a[i]=read();b[i]=read();
		if(a[i]!=4)c[++c[0]]=b[i];
	}
	disc_init();
	FOR(i,1,n){
		if(a[i]==1)modify(b[i],1);
		if(a[i]==2)modify(b[i],-1);
		if(a[i]==3)printf("%d\n",query_pos(b[i],3));
		if(a[i]==4)printf("%d\n",c[query_num(b[i])]);
		if(a[i]==5)printf("%d\n",c[query_num(query_pos(b[i],5))]);
		if(a[i]==6)printf("%d\n",c[query_num(query_pos(b[i],6))]);
	}
	return 0;
}