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HDU 1009：FatMouse' Trade（简单贪心）
FatMouse‘ Trade
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 41982 Accepted Submission(s): 13962
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
题意就是老鼠用猫粮换鼠粮。
。
。（Orz）。。
求它最多能换多少。。一道贪心水题。
。
#include<cstdio>
#include<cstring>
#include<string>
#include<algorithm>
#include<iostream>
#include<vector>
#include<queue>
#include<cmath>
#define f1(i, n) for(int i=0; i<n; i++)
#define f2(i, n) for(int i=1; i<=n; i++)
using namespace std;
const int M = 1005;
int n, m;
double ans;
double t;
struct node
{
double J;
double F;
double c;
}Q[M];
int cmp (node a, node b)
{
return a.c > b.c;
}
int main()
{
while(scanf("%d%d", &n, &m)!=EOF)
{
ans = 0;
t = (double) n;
memset(Q, 0, sizeof(Q));
if(n==-1 && m==-1)
break;
f1(i, m)
{
scanf("%lf%lf", &Q[i].J, &Q[i].F);
Q[i].c = Q[i].J / Q[i].F;
}
sort(Q, Q+m, cmp);
f1(i, m)
{
if( Q[i].F<=t )
{
ans += Q[i].J;
t -= Q[i].F;
}
else
{
ans += t * Q[i].c;
break;
}
}
printf("%.3lf\n", ans);
}
return 0;
}
HDU 1009：FatMouse' Trade（简单贪心）
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