Description

Give you a sequence and ask you the kth big number of a inteval.

Solution

主席树模板题

#include
     
      #include
      
       #include
       
        #include
        
         #include
         
          #define MAXN 100005using namespace std;int T,n,m,sz,tot;int a[MAXN],b[MAXN],rt[MAXN],ls[MAXN*20],rs[MAXN*20],sum[MAXN*20];int read(){    int x=0,f=1;char c=getchar();    while(c<'0'||c>'9'){        if(c=='-')f=-1;c=getchar();    }    while(c>='0'&&c<='9'){        x=x*10+c-'0';c=getchar();    }    return x*f;}void build(int &idx,int l,int r){    ++tot,idx=tot;sum[idx]=0;    if(l==r)return;    int mid=(l+r)>>1;    build(ls[idx],l,mid);    build(rs[idx],mid+1,r);}void insert(int &idx,int l,int r,int last,int pos){    ++tot,idx=tot;    ls[idx]=ls[last];    rs[idx]=rs[last];    sum[idx]=sum[last]+1;    if(l==r)return;    int mid=(l+r)>>1;    if(pos<=mid)insert(ls[idx],l,mid,ls[last],pos);    else insert(rs[idx],mid+1,r,rs[last],pos);}int query(int s,int t,int l,int r,int k){    if(l==r)return l;    int cnt=sum[ls[t]]-sum[ls[s]];    int mid=(l+r)>>1;    if(cnt>=k)return query(ls[s],ls[t],l,mid,k);    else return query(rs[s],rs[t],mid+1,r,k-cnt);}int main(){    T=read();    while(T--)    {        n=read(),m=read();tot=0;        for(int i=1;i<=n;i++)b[i]=a[i]=read();        sort(a+1,a+1+n);        sz=unique(a+1,a+1+n)-(a+1);        for(int i=1;i<=n;i++)b[i]=lower_bound(a+1,a+1+sz,b[i])-a;        build(rt[0],1,sz);        for(int i=1;i<=n;i++)        insert(rt[i],1,sz,rt[i-1],b[i]);        for(int i=1;i<=m;i++)        {            int s=read(),t=read(),k=read();            int ans=query(rt[s-1],rt[t],1,sz,k);            printf("%d\n",a[ans]);        }    }    return 0;}