[主席树] BZOJ1112: [POI2008]砖块Klo

#include<cstdio>
#include<algorithm>
#define mp(x,y) make_pair(x,y)
#define Fir first
#define Sec second
using namespace std;
typedef long long LL;
const int maxn=200005;
struct node{
node* ch[2]; int cnt; LL sum;
node(int t1=0,int t2=0){cnt=t1;sum=t2;ch[0]=ch[1]=0;}
void maintain(){
cnt=ch[0]->cnt+ch[1]->cnt;
sum=ch[0]->sum+ch[1]->sum;
}
} *rt[maxn];
typedef node* P_node;
P_node Build(int L,int R){
P_node p=new node();
if(L==R) return p;
int mid=(L+R)>>1;
p->ch[0]=Build(L,mid); p->ch[1]=Build(mid+1,R);
return p;
}
int n,m,a[maxn],b[maxn],ID[1000005];
P_node Updata(P_node pre,int L,int R,int pos){
P_node p=new node(pre->cnt,pre->sum); p->ch[0]=pre->ch[0]; p->ch[1]=pre->ch[1];
if(L==R){ p->cnt++; p->sum+=b[pos]; return p; }
int mid=(L+R)>>1;
if(pos<=mid) p->ch[0]=Updata(pre->ch[0],L,mid,pos);
else p->ch[1]=Updata(pre->ch[1],mid+1,R,pos);
p->maintain();
return p;
}
int Query(P_node p1,P_node p2,int L,int R,int now){
if(L==R) return L;
int mid=(L+R)>>1; int Lcnt=p1->ch[0]->cnt-p2->ch[0]->cnt;
if(Lcnt>=now) return Query(p1->ch[0],p2->ch[0],L,mid,now);
else return Query(p1->ch[1],p2->ch[1],mid+1,R,now-Lcnt);
}
pair<LL,int> Merge(pair<LL,int> A,pair<LL,int> B){ return mp(A.Fir+B.Fir,A.Sec+B.Sec); }
pair<LL,int> Query(P_node p1,P_node p2,int L,int R,int qL,int qR){
if(qR<L||R<qL||qL>qR) return mp(0,0);
if(qL<=L&&R<=qR) return mp(p1->sum-p2->sum,p1->cnt-p2->cnt);
int mid=(L+R)>>1;
return Merge(Query(p1->ch[0],p2->ch[0],L,mid,qL,qR),Query(p1->ch[1],p2->ch[1],mid+1,R,qL,qR));
}
LL ans;
int main(){
freopen("bzoj1112.in","r",stdin);
freopen("bzoj1112.out","w",stdout);
scanf("%d%d",&n,&m);
for(int i=1;i<=n;i++) scanf("%d",&a[i]), b[++b[0]]=a[i];
sort(b+1,b+1+n); b[0]=unique(b+1,b+1+b[0])-(b+1);
for(int i=1;i<=b[0];i++) ID[b[i]]=i;
rt[0]=Build(1,b[0]);
for(int i=1;i<=n;i++) rt[i]=Updata(rt[i-1],1,b[0],ID[a[i]]);
ans=1e+18;
for(int i=m;i<=n;i++){
int pos_mid=Query(rt[i],rt[i-m],1,b[0],(m+1)/2);
pair<LL,int> nowL=Query(rt[i],rt[i-m],1,b[0],1,pos_mid-1), nowR=Query(rt[i],rt[i-m],1,b[0],pos_mid+1,b[0]);
ans=min(ans,(LL)nowL.Sec*b[pos_mid]-nowL.Fir+nowR.Fir-(LL)nowR.Sec*b[pos_mid]);
}
printf("%lld\n",ans);
return 0;
}