FatMouse' Trade
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 54549 Accepted Submission(s): 18288
Problem Description
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 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.
Input
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.
Output
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.
Sample Input
5 3
7 2
4 3
5 2
20 3
25 18
24 15
15 10
-1 -1
Sample Output
13.333
31.500
Author
CHEN, Yue
Source
Recommend
一道基础的贪心,只需排序就好,运用了sort排序和结构体,感觉十分方便和强大。
题意:老鼠准备了M磅猫食,准备拿这些猫食跟猫交换自己喜欢的食物。有N个房间,每个房间里面都有食物。你可以得到J[i]但你需要付出F[i]的猫食。要你计算你有M磅猫食可以获得最多食物的重量。食物可以被分割。
附上代码:
1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4 #include <algorithm> 5 using namespace std; 6 struct node 7 { 8 int a,b; 9 double c; 10 }ss[1005]; 11 bool cmp(node x,node y) 12 { 13 return x.c>y.c; 14 } 15 int main() 16 { 17 int n,m,i,j,k,w; 18 double s; 19 while(cin>>n>>m) 20 { 21 if(n==-1&&m==-1) 22 break; 23 s=0; 24 for(i=0;i<m;i++) 25 { 26 cin>>ss[i].a>>ss[i].b; 27 ss[i].c=(double)ss[i].a/(double)ss[i].b; //求性价比,每元钱可以换多少这种食物 28 } 29 sort(ss,ss+m,cmp); //按性价比大小排序,单价买的越多,性价比越高 30 for(i=0;i<m;i++) 31 { 32 if(n>=ss[i].b) //拥有的钱超过这个食物全部的价格 33 { 34 s+=ss[i].a; //全部食物的重量 35 n-=ss[i].b; //减去花费的钱 36 } 37 else //若不够买这种食物的全部 38 { 39 s+=ss[i].c*n; //花光所有的钱购买这种食物 40 break; //钱为0,跳出循环 41 } 42 } 43 printf("%.3lf ",s); //保存3位小数输出 44 } 45 return 0; 46 }