http://codeforces.com/problemset/problem/919/A Supermarket

部分背包。

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define PI (M_PI)
#define INF (0x3f3f3f3f)
#define MOD (1000000007)
#define EPS (1e-12)
#define MAX (1000000)
#define LEN (MAX+5)
int main()
{
    int n,m;
    cin >> n >> m;
    int x,y;
    double ans = INF;
    for(int i = 1;i <= n;++i){
        scanf("%d%d",&x,&y);
        ans = min(ans,1.0*x / y);
    }
    printf("%.8lf\n",ans *m);
    return 0;
}