bzoj1082

题解：

暴搜+二分+剪枝

二分答案，暴力判断是否有解

然后加上剪枝

代码：

#include<bits/stdc++.h>
using namespace std;
const int N=;
int rest,c[N],sum[N],s,a[N],n,m,b[N];
int dfs(int x,int y)
{
    if (x<=)return ;
    if (rest+sum[x]>s)return ;
    for (int i=y;i<=n;i++)
     if (c[i]>=b[x])
      {
         c[i]-=b[x];
         if (c[i]<b[])rest+=c[i];
         if (b[x]==b[x-]){if (dfs(x-,i))return ;}
         else {if (dfs(x-,))return ;}
         if (c[i]<b[])rest-=c[i];
         c[i]+=b[x];
      }
    return ;
}
int pd(int x)
{
    for (int i=;i<=n;i++)c[i]=a[i];
    rest=;
    return dfs(x,);
}
int main()
{
    scanf("%d",&n);
    for (int i=;i<=n;i++)scanf("%d",&a[i]),s+=a[i];
    scanf("%d",&m);
    for (int i=;i<=m;i++)scanf("%d",&b[i]);
    sort(a+,a+n+);sort(b+,b+m+);
    for (int i=;i<=m;i++)sum[i]=sum[i-]+b[i];
    while (sum[m]>s)m--;
    int l=,r=m;
    while (l<r)
     {
         int mid=(l+r)/;
         if (pd(mid+))l=mid+;
         else r=mid;
     }
    printf("%d",l);
}