Luogu1090合并果子[单调队列]

/*
ID:hh826532
PROB:
LANG:C++
*/
#define _FILE_ ""
#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<string.h>
#include<math.h>
#include<vector>
#include<map>
#include<queue>
#include<time.h>
#include<fstream>
#include<string>
#include<set>
#include<list>
#include<stdlib.h>
#define fr(i,a,b) for(int i=a,_end_=b;i<=_end_;i++)
#define fd(i,a,b) for(int i=a,_end_=b;i>=_end_;i--)
#define frei(s) freopen(s,"r",stdin)
#define freo(s) freopen(s,"w",stdout)
#define ll long long
#define u unsigned
using namespace std;
#define rt return
#define inf 0x3f3f3f3f
#define infll 4557430888798830399ll
#define pc(x) putchar(x)
#define spc putchar(' ')
#define gc getchar()
#define ln pc('\n')
#define writeint(x) printf("%d",x)
#define lowbit(x) (x&(-x))
int readuint(){
int s=0;
char c=getchar();
while(c<'0'||c>'9')c=gc;
while(c>=48&&c<='9'){
s=s*10+c-48;
c=gc;
}
rt s;
}
int readint(){
int s=0,k=1;
char c=getchar();
while((c<'0'||c>'9')&&c!='-')c=gc;
if(c=='-'){
k=-1;
c=gc;
}
while(c>=48&&c<='9'){
s=s*10+c-48;
c=gc;
}
rt s*k;
}
void OPENFILE(){
char FILENAME[50];
if(strlen(_FILE_)==0)rt;
sprintf(FILENAME,"%s.in",_FILE_);
frei(FILENAME);
sprintf(FILENAME,"%s.out",_FILE_);
freo(FILENAME);
}
int alen,al,bl,blen,a[100010],b[100010],ans;
int main(){
OPENFILE();
alen=readuint();
if(alen<2)
{
printf("0\n");
rt 0;
}
fr(i,1,alen)
a[i]=readuint();
sort(a+1,a+alen+1);
blen=1;
al=3;
bl=1;
a[alen+1]=inf;
ans=b[1]=a[1]+a[2];
b[2]=inf;
fr(i,1,alen-2)
{
blen++;
b[blen]=0;
fr(j,1,2)
if(a[al]>b[bl]&&bl!=blen)
{
b[blen]+=b[bl];
bl++;
}
else
{
b[blen]+=a[al];
al++;
}
ans+=b[blen];
b[blen+1]=inf;
}
printf("%d\n",ans);
rt 0;
}