HDU 1114 Piggy-Bank

#include <cstdio>
using namespace std;
int e,b,n;
int f[10005];
int p[505],w[505];
int main(){
int t;
scanf("%d",&t);
while(t--){
scanf("%d%d",&e,&b);
e=b-e;
scanf("%d",&n);
for(int i=1;i<=n;i++)scanf("%d%d",&p[i],&w[i]);
for(int i=1;i<=e;i++)f[i]=1e9;
f[0]=0;
for(int i=1;i<=n;i++){
for(int j=w[i];j<=e;j++){
if(f[j-w[i]]+p[i]<f[j])f[j]=f[j-w[i]]+p[i];
}
}
if(f[e]==1e9)printf("This is impossible.\n");
else printf("The minimum amount of money in the piggy-bank is %d.\n",f[e]);
}

return 0;
}