题意:

  告诉你存钱罐中的钱的重量。 求钱的价值最少有多少。

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
const int mx = 502;
const int inf = 5e8 + 10;   //刚开始inf写小了
int f[11000], w[mx], v[mx];   // f也开小了
int main(){
    int t, n, a, b, c;
    scanf("%d", &t);
    while(t--){
      memset(f, 63, sizeof(f));
      scanf("%d %d", &a, &b);
      c = b - a;
      scanf("%d", &n);
      f[0] = 0;
      for(int i = 1; i <=n; i++)
        scanf("%d %d",&v[i], &w[i]);   
      for(int i = 1; i <= n; i++)
        for(int m = w[i]; m <= c; m++){
          f[m] = min( f[m - w[i]] + v[i], f[m]);  
      }
    if(f[c] > inf)
      puts("This is impossible.");
    else
      printf("The minimum amount of money in the piggy-bank is %d.\n", f[c]);
  }
         
  return 0; 
}