POJ 2184 Cow Exhibition 01背包变型 好题

 1 #include<cstdio>
 2 #include<cstring>
 3 
 4 const int maxn=200000+10;
 5 const int inf=0x3f3f3f3f;
 6 
 7 int dp[maxn];
 8 int s[105];
 9 int f[105];
10 
11 int max(int a,int b)
12 {
13     return a>b?a:b;
14 }
15 
16 int main()
17 {
18     int n;
19     while(~scanf("%d",&n))
20     {
21         int up=100000,down=100000;
22         for(int i=1;i<=n;i++)
23         {
24             scanf("%d%d",&s[i],&f[i]);
25             if(s[i]>0)
26                 up+=s[i];
27             else
28                 down+=s[i];
29         }
30 
31         for(int i=down;i<=up;i++)
32             dp[i]=-inf;
33         dp[100000]=0;
34         for(int i=1;i<=n;i++)
35         {
36             if(s[i]<=0&&f[i]<=0)
37                 continue;
38             if(s[i]>0)
39             {
40                 for(int j=up;j>=down+s[i];j--)
41                 {
42                     dp[j]=max(dp[j],dp[j-s[i]]+f[i]);
43                 }
44             }
45             else
46             {
47                 for(int j=down;j<=up+s[i];j++)
48                 {
49                     dp[j]=max(dp[j],dp[j-s[i]]+f[i]);
50                 }
51             }
52         }
53         int ans=0;
54         for(int i=100000;i<=up;i++)
55         {
56             if(dp[i]>=0)
57                 ans=max(ans,i+dp[i]-100000);
58         }
59         printf("%d\n",ans);
60     }
61     return 0;
62 }