POJ2184——背包DP——Cow Exhibition

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
const int inf = 0x3f3f3f3f;
const int MAX = 100000+5;
int dp[2*MAX];
int a[105],b[105];
int main()
{
    int x,y;
    int T;
    while(~scanf("%d",&T)){
        memset(a,0,sizeof(a));
        memset(b,0,sizeof(b));
        for(int i = 1 ; i <= T; i++){
            scanf("%d%d",&a[i],&b[i]);
        }
        for(int i = 0; i <= 200000;i++)
            dp[i] = -inf;
        dp[100000] = 0;
        for(int i = 1; i <= T; i++){
            if(a[i] < 0 && b[i] < 0)
                continue;
            else if(a[i] > 0){
                for(int j = 200000; j >= a[i]; j--){
                     if(dp[j-a[i]] > - inf){
                  dp[j] = max(dp[j],dp[j-a[i]] + b[i]);
                     }
                }
            }
            else {
                for(int j = a[i]; j <= 200000+a[i]; j++){
                    if(dp[j-a[i]] > -inf){
                    dp[j] = max(dp[j],dp[j-a[i]]+b[i]);
                    }
                }
            }        
        }
        int max1 = -inf;
        for(int i = 100000; i <= 200000; i++){
            if(dp[i] >= 0)
            max1 = max(max1,dp[i]+i-100000);
                }
                printf("%d\n",max1);
            }
        return 0;
}