题目E：Fat Mouse's Trade
FatMouse prepared M pounds of cat food, ready to trade with the cats guarding the warehouse containing his favorite food, JavaBean.
The warehouse has N rooms. The i-th room contains J[i] pounds of JavaBeans and requires F[i] pounds of cat food. FatMouse does not have to trade for all the JavaBeans in the room, instead, he may get J[i]* a% pounds of JavaBeans if he pays F[i]* a% pounds of cat food. Here a is a real number. Now he is assigning this homework to you: tell him the maximum amount of JavaBeans he can obtain.The input consists of multiple test cases. Each test case begins with a line containing two non-negative integers M and N. Then N lines follow, each contains two non-negative integers J[i] and F[i] respectively. The last test case is followed by two -1's. All integers are not greater than 1000.
For each test case, print in a single line a real number accurate up to 3 decimal places, which is the maximum amount of JavaBeans that FatMouse can obtain.
数据范围：all integers<=1000.
输入样例：
5 3
7 2
4 3
5 2
20 3
25 18
24 15
15 10
-1 -1
输出样例：
13.333
31.500
题解思路：
此题类似01背包问题，但可以不装完，所以可以用贪心算法解决。
对每一次交易的比率从大到小排序，选取最大比率的交易依次进行。
例如样例1，计算出每个交易的比率J[i]/F[i]，分别为3.5，1.33，2.5，所以先用2个猫粮买7个咖啡豆，再用2个猫粮买5个咖啡豆，之后只剩1咖啡豆，可以买4/3个咖啡豆，总共获得13.333个。
题解：
#include<iostream>
#include<algorithm>
using namespace std;
struct warehouse{
int j,f;
double rate;
}p[1007];
bool compare(warehouse a,warehouse b){
return a.rate>b.rate;
}
int main(){
int m,n;
double r=0;
while(true){
scanf("%d%d",&m,&n);
if(m==-1){
return 0;
}
for(int i=0;i<n;i++){ //calculate each rate of the warehouse
scanf("%d%d",&p[i].j,&p[i].f);
p[i].rate=(double)(p[i].j)/(double)(p[i].f);
}
sort(p,p+n,compare);
r=0;
for(int i=0;i<n;i++){
if(m>0){
if(m>=p[i].f){
r+=(double)p[i].j;
m-=p[i].f;
}
else{
r+=(double)p[i].j*(double)m/(double)p[i].f;
break;
}
}
else{
break;
}
}
printf("%.3lf\n",r);
}
}
题目F：
数据范围：
输入样例：
输出样例：
题解思路：
题解：
题目G：
数据范围：
输入样例：
输出样例：
题解思路：
题解：
题目H：
数据范围：
输入样例：
输出样例：
题解思路：
题解：
题目I：
数据范围：
输入样例：
输出样例：
题解思路：
题解：
题目J：
数据范围：
输入样例：
输出样例：
题解思路：
题解：
题目K：
数据范围：
输入样例：
输出样例：
题解思路：
题解：
