Codeforces Round #460 (Div. 2)-A Supermaket(贪心)
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.
贪心,做商排序即可。
#include <bits/stdc++.h>
using namespace std;
template <typename t>
void read(t &x)
{
char ch = getchar();
x = 0;
t f = 1;
while (ch < '0' || ch > '9')
f = (ch == '-' ? -1 : f), ch = getchar();
while (ch >= '0' && ch <= '9')
x = x * 10 + ch - '0', ch = getchar();
x *= f;
}
#define wi(n) printf("%d ", n)
#define wl(n) printf("%lld ", n)
#define rep(m, n, i) for (int i = m; i < n; ++i)
#define rrep(m, n, i) for (int i = m; i > n; --i)
#define P puts(" ")
typedef long long ll;
#define MOD 1000000007
#define mp(a, b) make_pair(a, b)
#define N 10005
#define fil(a, n) rep(0, n, i) read(a[i])
//---------------https://lunatic.blog.csdn.net/-------------------//
#define maxn 5005
struct Pay
{
double w;
double v;
double pri;
} s[maxn];
int cmp(Pay a, Pay b)
{
return a.pri < b.pri;
}
int main()
{
int m, i, n;
Pay s[maxn];
read(m), read(n);
for (i = 0; i < m; i++)
{
scanf("%lf%lf", &s[i].v, &s[i].w);
s[i].pri = s[i].v / s[i].w;
}
sort(s, s + m, cmp);
printf("%.10f", n * s[0].pri);
return 0;
}
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