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;}