静态区间第K大，主席树。。。。
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Feed the dogs
Description Wind loves pretty dogs very much, and she has n pet dogs. So Jiajia has to feed the dogs every day for Wind. Jiajia loves Wind, but not the dogs, so Jiajia use a special way to feed the dogs. At lunchtime, the dogs will stand on one line, numbered from 1 to Your task is to help Jiajia calculate which dog ate the food after each feeding. Input The first line contains n and m, indicates the number of dogs and the number of feedings. The second line contains n integers, describe the pretty value of each dog from left to right. You should notice that the dog with lower pretty value is prettier. Each of following m lines contain three integer i,j,k, it means that Jiajia feed the k-th pretty dog in this feeding. You can assume that n<100001 and m<50001. Output Output file has m lines. The i-th line should contain the pretty value of the dog who got the food in the i-th feeding. Sample Input 7 2 1 5 2 6 3 7 4 1 5 3 2 7 1 Sample Output 3 2 Source POJ Monthly--2006.02.26,zgl & twb |
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#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
const int maxn=110000;
int n,m,q;
int a[maxn],t[maxn];
int tot,T[maxn],lson[maxn*30],rson[maxn*30],c[maxn*30];
void hash_init()
{
sort(t+1,t+1+n);
m=unique(t+1,t+1+n)-t;
}
int hash(int x)
{
return lower_bound(t+1,t+1+m,x)-t;
}
int build(int l,int r)
{
int root=tot++,temp=root;
c[root]=0;
if(l!=r)
{
int mid=(l+r)/2;
lson[root]=build(l,mid);
rson[root]=build(mid+1,r);
}
return temp;
}
int update(int root,int pos,int val)
{
int newroot=tot++,temp=newroot;
c[newroot]=c[root]+val;
int l=1,r=m;
while(l<r)
{
int mid=(l+r)/2;
if(pos<=mid)
{
lson[newroot]=tot++; rson[newroot]=rson[root];
root=lson[root]; newroot=lson[newroot];
r=mid;
}
else
{
rson[newroot]=tot++; lson[newroot]=lson[root];
root=rson[root]; newroot=rson[newroot];
l=mid+1;
}
c[newroot]=c[root]+val;
}
return temp;
}
int query(int left_root,int right_root,int x)
{
int l=1,r=m;
while(l<r)
{
int mid=(l+r)/2;
int tt=c[lson[left_root]]-c[lson[right_root]];
if(tt>=x)
{
left_root=lson[left_root];
right_root=lson[right_root];
r=mid;
}
else
{
x-=tt;
left_root=rson[left_root];
right_root=rson[right_root];
l=mid+1;
}
}
return l;
}
int main()
{
while(scanf("%d%d",&n,&q)!=EOF)
{
memset(c,0,sizeof(c)); tot=0;
for(int i=1;i<=n;i++)
{
scanf("%d",a+i);
t[i]=a[i];
}
hash_init();
T[n+1]=build(1,m);
for(int i=n;i;i--)
{
T[i]=update(T[i+1],hash(a[i]),1);
}
while(q--)
{
int a,b,c;
scanf("%d%d%d",&a,&b,&c);
printf("%d\n",t[query(T[a],T[b+1],c)]);
}
}
return 0;
}
POJ 2761 Feed the dogs