动态区间第K大

整体二分。 

主要需要注意的一点是，对于每个删除操作，若删除操作被算入贡献，则最开始的插入操作也一定会被算入，所以不必担心删除删错。

#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
#define LL  long long
#define FILE "dealing"
#define up(i,j,n) for(int i=j;i<=n;i++)
int read(){
	int x=0,f=1,ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9')x=(x<<1)+(x<<3)+ch-'0',ch=getchar();
	return x*f;
}
const int maxn=800000,mod=1000000007,inf=10000000000000LL;
bool cmin(int& a,int b){return a>b?a=b,true:false;}
bool cmax(int& a,int b){return a<b?a=b,true:false;}
int ans[maxn];int n,m;
struct node{int x,y,k,id,op;}a[maxn],q1[maxn],q2[maxn];
char s[10];
int d[maxn],sum[maxn],v[maxn];
int lowbit(int x){return x&-x;}
void add(int x,int di){while(x<=n)d[x]+=di,x+=lowbit(x);}
int getsum(int x){int ans=0;while(x)ans+=d[x],x-=lowbit(x);return ans;}
void divide(int L,int R,int l,int r){
	if(l>r)return;
	if(L==R){
		up(i,l,r)if(a[i].op==2)ans[a[i].id]=L;
		return;
	}
	int mid=(L+R)>>1;
	up(i,l,r){
		if(a[i].op==1&&mid>=a[i].x)add(a[i].y,1);
		if(a[i].op==2)sum[i]=getsum(a[i].y)-getsum(a[i].x-1);
		if(a[i].op==3&&mid>=a[i].x)add(a[i].y,-1);
	}
	up(i,l,r){
		if(a[i].op==1&&mid>=a[i].x)add(a[i].y,-1);
		if(a[i].op==3&&mid>=a[i].x)add(a[i].y,1);
	}
	int top1=0,top2=0;
	up(i,l,r){
		if(a[i].op==2){
			if(sum[i]<=a[i].k){
				a[i].k-=sum[i];
				q2[++top2]=a[i];
			}else q1[++top1]=a[i];
		}
		else {
			if(a[i].x<=mid)q1[++top1]=a[i];
			else q2[++top2]=a[i];
		}
	}
	up(i,l,l+top1-1)a[i]=q1[i-l+1];
	up(i,l+top1,r)a[i]=q2[i-l-top1+1];
	divide(L,mid,l,l+top1-1);
	divide(mid+1,R,l+top1,r);
}
int main(){
	freopen(FILE".in","r",stdin);
	freopen(FILE".out","w",stdout);
	int T=read();
	while(T--){
		memset(ans,0,sizeof(ans));
		n=read(),m=read();int top=n;
		up(i,1,n){a[i].op=1;v[i]=a[i].x=read(),a[i].y=i,a[i].id=i;}
		up(i,1,m){
			scanf("%s",s);
			if(s[0]=='Q')a[++top].op=2,a[top].x=read(),a[top].id=i,a[top].y=read(),a[top].k=read()-1;
			else a[++top].op=3,a[top].y=read(),a[top].x=v[a[top].y],a[++top].op=1,a[top].x=read(),a[top].y=a[top-1].y,v[a[top].y]=a[top].x;
		}
		divide(0,mod,1,top);
		up(i,1,m)if(ans[i])printf("%d\n",ans[i]);
	}
	return 0;
}