bzoj2006: [NOI2010]超级钢琴

#include<cstdio>
#include<cstring>
#include<cctype>
#include<algorithm>
#include<queue>
#include<cmath>
using namespace std;
#define rep(i,s,t) for(register int i=s;i<=t;i++)
#define dwn(i,s,t) for(register int i=s;i>=t;i--)
#define clr(x,c) memset(x,c,sizeof(x))
#define ll long long
int read(){
    int x=0,f=1;char c=getchar();
    while(!isdigit(c)){
        if(c==‘-‘) f=-1;c=getchar();
    }
    while(isdigit(c)) x=x*10+c-‘0‘,c=getchar();
    return x*f;
}
const int nmax=500005;
const int inf=0x7f7f7f7f;
struct node{
    int orz,mx,cur,l,r;
    node(int orz,int mx,int cur,int l,int r):orz(orz),mx(mx),cur(cur),l(l),r(r){};
    node(){};
    bool operator<(const node&rhs)const{
      return mx<rhs.mx;}
};
priority_queue<node>q;
int n,K,L,R,a[nmax];
struct zs{
    int u,v;
};
zs f[nmax][20];
zs query(int l,int r){
    int t=log(r-l+1)/log(2);
    if(f[l][t].u>f[r-(1<<t)+1][t].u) return f[l][t];
    else return f[r-(1<<t)+1][t];
}
void init(){
    rep(i,1,n) f[i][0].u=a[i],f[i][0].v=i;
    rep(i,1,19){
        if((1<<i)>n) break;
        rep(j,1,n-1){
            if(j+(1<<i)-1>n) break;
            if(f[j][i-1].u>f[j+(1<<i-1)][i-1].u) f[j][i]=f[j][i-1];
            else f[j][i]=f[j+(1<<i-1)][i-1];
        }
    }
}
int main(){
    n=read(),K=read(),L=read(),R=read();
    rep(i,1,n) a[i]=read()+a[i-1];
    init();
    int l,r;
    rep(i,1,n-L+1){
        l=i+L-1,r=min(i+R-1,n);zs o=query(l,r);
        q.push(node(i,o.u-a[i-1],o.v,l,r));
    }
    ll ans=0;node o;zs oo;
    rep(i,1,K){
        o=q.top();q.pop();
        ans+=o.mx;
        if(o.cur-1>=o.l) {
            oo=query(o.l,o.cur-1);
            q.push(node(o.orz,oo.u-a[o.orz-1],oo.v,o.l,o.cur-1));
        }
        if(o.cur+1<=o.r){
            oo=query(o.cur+1,o.r);
            q.push(node(o.orz,oo.u-a[o.orz-1],oo.v,o.cur+1,o.r));
        }
    }
    printf("%lld\n",ans);
    return 0;
}