poj-1384 Piggy-Bank

#include <iostream> 
#include <cstdio> 
#include <cstdlib> 
#include <cstring> 
#include <string> 
using namespace std; 
const int maxn = 505; 
const int max_val = 10000; 

int E,F, n, dp[max_val+5]; 

struct Node{
    int p,w; 
}nd[maxn]; 

int cmp(const void* a, const void* b){
    Node* aa = (Node *)a; 
    Node* bb = (Node *)b; 
    return (bb->w*1.0)/(bb->p*1.0) - (aa->w*1.0)/(aa->p*1.0);  
}

int main(){
    freopen("in.txt", "r", stdin); 

    int test_num, i, j; 
    scanf("%d", &test_num); 
    while(test_num--){
        scanf("%d %d", &E, &F); 
        scanf("%d", &n); 
        for(i=0; i<n; i++){
            scanf("%d %d", &nd[i].p, &nd[i].w); 
        }
        memset(dp, 0x3f3f3f3f, sizeof(dp));  
        dp[0] = 0; 
        for(i=0; i<n; i++){
            for(j=nd[i].w; j<=(F-E); j++){
                if(dp[j - nd[i].w] != 0x3f3f3f3f ){
                    dp[j] = min(dp[j-nd[i].w]+nd[i].p, dp[j]); 
                }
            }
        }
        if(dp[F-E] == 0x3f3f3f3f){
            printf("This is impossible.\n");
        }else{
            printf("The minimum amount of money in the piggy-bank is %d.\n", dp[F-E]);
        }
    }
    return 0; 
}