BZOJ2006【主席树】【优先队列】

/* I will wait for you */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<ctime>
#include<algorithm>
#include<iostream>
#include<fstream>
#include<vector>
#include<queue>
#include<deque>
#include<set>
#include<map>
#include<string>

typedef long long LL;
typedef unsigned long long ULL;

using namespace std;

const int maxn=100010;
const int maxm=500000010;
const int maxs=26;
const int INF=1<<29;
const int P=1000000007;
const double error=1e-9;

struct node
{
int l,r,sum;node *son[2];
node(int x,int y) { l=x;r=y;sum=0;son[0]=son[1]=0; }
}*su[maxn];

struct ans{ int key,id,k; };

int n,k,L,R,c[maxn],ml[maxn],mr[maxn];

bool operator < (ans a,ans b) { return a.key<b.key; }

priority_queue<ans> q;

void maintain(node* o)
{
o->sum=0;
for(int i=0;i<2;i++) if(o->son[i]) o->sum+=o->son[i]->sum;
}

node* insert(node* o,int c,int x,int y)
{
node* p=new node(x,y);
if(x==y) p->sum=o?o->sum+1:1;
else
{
int mid=x+(y-x)/2;
node *ls=o?o->son[0]:0,*rs=o?o->son[1]:0;
if(c<=mid) p->son[0]=insert(ls,c,x,mid),p->son[1]=rs;
if(c>mid) p->son[1]=insert(rs,c,mid+1,y),p->son[0]=ls;
maintain(p);
}
return p;
}

int rank(node* x,node* y,int l,int r,int k)
{
if(l==r) return (l+r)/2;
int mid=l+(r-l)/2;
int xs=x&&x->son[0]?x->son[0]->sum:0;
int ys=y&&y->son[0]?y->son[0]->sum:0;

int d=(k>ys-xs);
node *sx=x?x->son[d]:0,*sy=y?y->son[d]:0;

if(k<=ys-xs) return rank(sx,sy,l,mid,k);
else return rank(sx,sy,mid+1,r,k-(ys-xs));
}

int kth(int l,int r,int k)
{
return rank(su[l-1],su[r],-maxm,maxm,k);
}

int main()
{
scanf("%d%d%d%d",&n,&k,&L,&R);

su[0]=insert(su[0],0,-maxm,maxm);

for(int i=1;i<=n;i++)
{
scanf("%d",&c[i]);c[i]+=c[i-1];
su[i]=insert(su[i-1],c[i],-maxm,maxm);
ml[i]=max(0,i-R);mr[i]=max(0,i-L);
if(i>=L) q.push((ans){c[i]-kth(ml[i],mr[i],1),i,1});
}

LL fin=0;
for(int i=1;i<=k;i++)
{
ans p=q.top();q.pop();fin+=p.key;
if(p.k<=mr[p.id]-ml[p.id])
q.push((ans){c[p.id]-kth(ml[p.id],mr[p.id],p.k+1),p.id,p.k+1});
}

printf("%lld\n",fin);
return 0;
}