BZOJ 1082: [SCOI2005]栅栏|二分答案爆搜

#include<set>
#include<map>
#include<ctime>
#include<queue>
#include<cmath>
#include<cstdio>
#include<vector>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define T 1006
#define MX 1e9
using namespace std;
int sc()
{
int i=0,f=1; char c=getchar();
while(c>'9'||c<'0'){if(c=='-')f=-1;c=getchar();}
while(c>='0'&&c<='9')i=i*10+c-'0',c=getchar();
return i*f;
}
int h[55],nd[T],sum[T],bl[T],n,m,S,mid;
bool dfs(int x,int y,int rest)
{
if(y==0)return 1;
while(x<=n&&h[x]<nd[1])rest+=h[x],x++;
if(sum[mid]>S-rest)return 0;
int t=x;
if(nd[y]==nd[y+1]&&y!=mid)t=bl[y+1];
for(int i=t;i<=n;i++)
if(h[i]>=nd[y])
{
bl[y]=i;
h[i]-=nd[y];
if(dfs(x,y-1,rest))
{
h[i]+=nd[y];
return 1;
}
else h[i]+=nd[y];
}
return 0;
}
int main()
{
n=sc();for(int i=1;i<=n;i++)h[i]=sc(),S+=h[i];
m=sc();for(int i=1;i<=m;i++)nd[i]=sc();
sort(h+1,h+n+1),sort(nd+1,nd+m+1);
while(nd[m]>h
)m--;
for(int i=1;i<=m;i++)sum[i]=sum[i-1]+nd[i];
int l=0,r=m,ans=0;
while(l<=r)
{
mid=l+r>>1;
if(dfs(1,mid,0))ans=mid,l=mid+1;
else r=mid-1;
}
cout<<ans;
return 0;
}