【HDOJ】3033 I love sneakers!

分组背包。

 #include <stdio.h>
 #include <string.h>

 #define mymax(a, b) (a>b) ? a:b

 typedef struct {
     int p, v;
 } shoe_st;

 shoe_st shoes[][];
 int dp[][];
 int len[];

 int main() {
     int n, m, k, g, p, v;
     int i, j, flg, t;

     while (scanf("%d%d%d",&n,&m,&k) != EOF) {
         memset(len, , sizeof(len));
         for (i=; i<=n; ++i) {
             scanf("%d%d%d", &g, &p, &v);
             len[g]++;
             shoes[g][len[g]].p = p;
             shoes[g][len[g]].v = v;
         }
         memset(dp, -, sizeof(dp));
         dp[][] = ;
         flg = ;
         for (i=; i<=k; ++i) {
             if (len[i] == ) {
                 flg = ;
                 break;
             }
             for (t=; t<=len[i]; ++t) {
                 for (j=m; j>=shoes[i][t].p; --j) {
                     if (dp[i][j-shoes[i][t].p] != -) {
                         dp[i][j] = mymax(dp[i][j], dp[i][j-shoes[i][t].p]+shoes[i][t].v);
                     }
                     if (dp[i-][j-shoes[i][t].p] != -) {
                         dp[i][j] = mymax(dp[i][j], dp[i-][j-shoes[i][t].p]+shoes[i][t].v);
                     }
                 }
             }
         }
         if (flg) {
             t = -;
             for (j=; j<=m; ++j) {
                 if (dp[k][j] > t)
                     t = dp[k][j];
             }
             if (t > -)
                 printf("%d\n", t);
             else
                 printf("Impossible\n");
         } else {
             printf("Impossible\n");
         }
     }

     return ;
 }