Cow Exhibition [POJ2184] [DP] [背包的负数处理]

 1 #include<set>
 2 #include<map>
 3 #include<queue>
 4 #include<stack>
 5 #include<cmath>
 6 #include<cstdio>
 7 #include<cstring>
 8 #include<iostream>
 9 #include<algorithm>
10 #define RG register int
11 #define rep(i,a,b)    for(RG i=a;i<=b;++i)
12 #define per(i,a,b)    for(RG i=a;i>=b;--i)
13 #define ll long long
14 #define inf (1<<29)
15 #define O 100000
16 #define maxn 105
17 #define maxm 200005
18 using namespace std;
19 int n;
20 int dp[maxm],v[maxn],w[maxn];
21 inline int read()
22 {
23     int x=0,f=1;char c=getchar();
24     while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=getchar();}
25     while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=getchar();}
26     return x*f;
27 }
28 int main()
29 {
30     n=read();
31     rep(i,1,n)    w[i]=read(),v[i]=read();
32     //memset(dp,-63,sizeof(dp));
33     dp[O]=0;
34     rep(i,1,n)
35     {
36         if(v[i]>=0)
37             per(j,maxm-1,v[i])
38                 dp[j]=max(dp[j],dp[j-v[i]]+w[i]);
39         else
40             rep(j,0,maxm-1+v[i])
41                 dp[j]=max(dp[j],dp[j-v[i]]+w[i]);
42     }
43     int ans=0;
44     rep(i,O,maxm-1)
45         if(dp[i]>=0)
46             ans=max(ans,dp[i]+i-O);
47     cout<<ans;
48     return 0;
49 }