poj 2184 Cow Exhibition 负值01背包

#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
const int inf=1<<24;

int dp[200000+5],s[100+5],f[10+5];

int main()
{
int n,i,j,ans;
while(~scanf("%d",&n))
{
for(i=0;i<n;i++)
scanf("%d%d",&s[i],&f[i]);
for(i=0;i<=200000;i++)
dp[i]=-inf;
dp[100000]=0;

for(i=0;i<n;i++)
{
if(s[i]<=0&&f[i]<=0) continue;
if(s[i]>0)
{
for(j=200000;j>=s[i];j--)

if(dp[j-s[i]]>-inf)
dp[j]=max(dp[j-s[i]]+f[i],dp[j]);
}
else
{
for(j=s[i];j<=200000+s[i];j++)
{
if(dp[j-s[i]]>-inf)
dp[j]=max(dp[j-s[i]]+f[i],dp[j]);
}
}
}

ans=-inf;
for(i=100000;i<=200000;i++)
{
if(dp[i]>=0)//要求两个都要大于0
ans=max(ans,dp[i]+i-100000);
}

printf("%d\n",ans);
}
return 0;
}