Fence Rails

 1 #include<cstdio>
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 int n,m;
 6 int a[55],value[1025];
 7 int b[55];
 8 int limit=1;
 9 int space=0;
10 int maxspace=0;
11 bool cmp(int a,int b)
12 {
13     return a>b;
14 }
15 int dfs(int cur,int start)
16 {
17     if(cur==m)
18     {
19         return 1;
20     }
21     space=0;
22     for(int i=0;i<n;i++)
23     {
24         if(b[i]<value[m-1]) space+=b[i];
25     }
26     if(space>maxspace) return 0;
27     for(int i=start;i<n;i++)
28     {
29         if(b[i]>=value[cur])
30         {
31             int st=0;
32             b[i]-=value[cur];
33             if(cur<m-1&&value[cur]==value[cur+1]) st=i; 
34             if(dfs(cur+1,st)) return 1;
35             b[i]+=value[cur];
36         }
37     }
38     return 0;
39 }
40 int main()
41 {
42     scanf("%d",&n);
43     for(int i=0;i<n;i++)
44     {
45         scanf("%d",&a[i]);
46     }
47     sort(a,a+n,cmp);
48     scanf("%d",&m);
49     for(int i=0;i<m;i++)
50     {
51         scanf("%d",&value[i]);
52     }
53     sort(value,value+m,cmp);
54     int left=0;
55     int right=m;
56     while(left<right)
57     {
58         int mid=left+(1+right-left)/2;
59         limit=mid;
60         maxspace=0;
61         for(int i=0;i<n;i++) maxspace+=a[i];
62         for(int i=m-limit;i<m;i++) maxspace-=value[i];
63         for(int i=0;i<n;i++) b[i]=a[i];
64         if(dfs(m-limit,0)) left=mid;
65         else right=mid-1;
66     }
67     printf("%d\n",left);
68     return 0;
69 }