【HDOJ】2333 Assemble

二分+贪心策略。其中注释处很重要。

 #include <iostream>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 #include <algorithm>
 using namespace std;

 #define MAXL 25
 #define MAXN 1005
 #define INF  1000000000

 typedef struct {
     char name[MAXL];
     int p, q;
 } comp_st;

 comp_st comps[MAXN];
 int t, n, b;
 int ns[MAXN], nn;

 bool comp(comp_st a, comp_st b) {
     int tmp = strcmp(a.name, b.name);
     if (tmp == )
         return a.q > b.q;
     else
         return tmp < ;
 }

 bool chk(int x) {
     int i, j;
     int sum = , min;

     for (i=; i<nn; ++i) {
         min = INF;
         for (j=ns[i]; j<ns[i+]; ++j) {
             if (comps[j].q>=x && min>comps[j].p)
                 min = comps[j].p;
         }
         /* pay attention to here.*/
         if (min == INF)
             return false;
         sum += min;
     }
     return sum<=b;
 }

 int main() {
     int i, min, max, mid, v;
     char str[MAXL];

     scanf("%d", &t);

     while (t--) {
         scanf("%d %d", &n, &b);
         min = INF;
         max = ;
         for (i=; i<n; ++i) {
             scanf("%s %s %d %d", comps[i].name, str, &comps[i].p, &comps[i].q);
             if (comps[i].q < min) min = comps[i].q;
             if (comps[i].q > max) max = comps[i].q;
         }
         sort(comps, comps+n, comp);
         ns[] = ;
         for (nn=,i=; i<n; ++i) {
             if (strcmp(comps[i-].name, comps[i].name) != )
                 ns[++nn] = i;
         }
         ns[++nn] = n;
         v = ;
         while (min <= max) {
             mid = (min+max)/;
             if ( chk(mid) ) {
                 v = mid;
                 min = mid+;
             } else {
                 max = mid-;
             }
         }
         printf("%d\n", v);
     }

     return ;
 }