hdoj 1009 FatMouse' Trade 【贪心】

题目链接 http://acm.hdu.edu.cn/showproblem.php?pid=1009

 

思路:先求出每一个仓库的交换价值率（就是一个F能交换多少J），然后按照交换率排序，依次判断相加就可以了

代码：

#include<cstdio>#include<algorithm>using std::sort;typedef struct{double j, f;double rat;}str;str s[1005];int cmp(str a, str b){return a.rat > b.rat;}int main(){double m; int i, j, n;while(scanf("%lf%d", &m, &n), n != -1&&m !=-1){for(i = 0; i < n; i ++){scanf("%lf%lf", &s[i].j, &s[i].f);s[i].rat = s[i].j/s[i].f; //求交换价值率//printf("%lf %lf %lf\n", s[i].j, s[i].f, s[i].rat);}sort(s, s+n, cmp);double sum = 0;for(i = 0; i < n; i ++){if(m>=s[i].f){ //判断能不能全部交换sum+=s[i].j;//printf("%lf,,", sum);m -= s[i].f;}else{sum += s[i].rat*m;m-=m;break;}}printf("%.3lf\n", sum);}return 0;}