Codeforces 919 A. Supermarket
这场cf有点意思,hack场,C题等于1的特判hack很多人(我hack成功3个人,上分了,哈哈哈,咳咳。。。)
D题好像是树形dp,E题好像是中国剩余定理,F题好像还是dp,具体的不清楚,最近dp的题目好多,一会滚去学dp。
写A,B,C的题解。
2 seconds
256 megabytes
standard input
standard output
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.
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.
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 .
3 5
1 2
3 4
1 3
1.66666667
2 1
99 100
98 99
0.98989899
In the first sample, you are supposed to buy 5 kilos of apples in supermarket 3. The cost is 5 / 3 yuan.
In the second sample, you are supposed to buy 1 kilo of apples in supermarket 2. The cost is 98 / 99 yuan.
大水题。
代码:
#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cstdlib>
#include<string.h>
#include<set>
#include<vector>
#include<queue>
#include<stack>
#include<map>
#include<cmath>
using namespace std;
const int inf=0x3f3f3f3f;
int main(){
double a,b,ans;
double minn=inf;
int n,m;
cin>>n>>m;
for(int i=;i<n;i++){
cin>>a>>b;
if(minn>a/b) minn=1.0*a/b;
}
ans=minn*(double)m;
printf("%.8lf",ans);
}
滚去学dp,学会了补后面的题|ू・ω・` )
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