【HDOJ】1114 Piggy-Bank

DP，先将coins按照重量排序可以优化。

 #include <stdio.h>
 #include <stdlib.h>

 #define MAXNUM  10005
 #define COINNUM 505
 #define MAXVAL  0x7fffffff
 #define MYMIN(a, b) a<b ? a:b

 typedef struct {
     int weight, val;
 } coin_st;

 coin_st coins[COINNUM];
 int dp[MAXNUM];
 int e, f;

 int comp(const void *a, const void *b) {
     return ((coin_st*)a)->weight - ((coin_st*)b)->weight;
 }

 int main() {
     int case_n, n;
     int i, j, left;

     scanf("%d", &case_n);
     dp[] = ;
     while (case_n--) {
         scanf("%d %d", &e, &f);
         scanf("%d", &n);
         for (i=; i<n; ++i)
             scanf("%d %d", &coins[i].val, &coins[i].weight);
         qsort(coins, n, sizeof(coin_st), comp);

         for (i=; i<=f-e; ++i) {
             dp[i] = MAXVAL;
             for (j=; j<n; ++j) {
                 left = i-coins[j].weight;
                 if (left<)
                     break;
                 if (dp[left]!=MAXVAL && dp[left]+coins[j].val < dp[i])
                     dp[i] = dp[left]+coins[j].val;
             }
         }
         if (dp[f-e] == MAXVAL)
             printf("This is impossible.\n");
         else
             printf("The minimum amount of money in the piggy-bank is %d.\n", dp[f-e]);
     }

     return ;
 }