A. Supermarket
time limit per test2 seconds
memory limit per test256 megabytes
Problem Description
We often go to supermarkets to buy some fruits or vegetables, and on the tag there prints the price for a kilo. But in some supermarkets, when asked how much the items are, the clerk will say that a yuan for b kilos (You don’t need to care about what “yuan” is), the same as a / b yuan for a kilo.
Now imagine you’d like to buy m kilos of apples. You’ve asked n supermarkets and got the prices. Find the minimum cost for those apples.
You can assume that there are enough apples in all supermarkets.
Input
The first line contains two positive integers n and m (1 ≤ n ≤ 5 000, 1 ≤ m ≤ 100), denoting that there are n supermarkets and you want to buy m kilos of apples.
The following n lines describe the information of the supermarkets. Each line contains two positive integers a, b (1 ≤ a, b ≤ 100), denoting that in this supermarket, you are supposed to pay a yuan for b kilos of apples.
Output
The only line, denoting the minimum cost for m kilos of apples. Please make sure that the absolute or relative error between your answer and the correct answer won’t exceed 10 - 6.
Formally, let your answer be x, and the jury’s answer be y. Your answer is considered correct if .
Examples
input
3 5
1 2
3 4
1 3
output
1.66666667
input
2 1
99 100
98 99
output
0.98989899
解题心得：
- 一个水题，注意精度问题就可以轻松过了。
#include<bits/stdc++.h>
using namespace std;
int main()
{
double ans,a,b,m;
int n;
scanf("%d%lf",&n,&m);
ans = 10000000.0;
for(int i=0;i<n;i++)
{
scanf("%lf%lf",&a,&b);
ans = min(ans,m*a/b);
}
printf("%.8f",ans);
return 0;
}