poj1922

简单题，但double的精度在单位转换除以3.6的时候居然会不够。所以应该不进行单位换算，在算时间时乘以3.6即可。

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#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;

#define maxn 10005

struct Rider
{
double s;
int t;
}rider[maxn];

int n, length = 4500;

bool operator < (const Rider &a, const Rider &b)
{
return a.t + length * 3.6 / a.s < b.t + length * 3.6 / b.s;
}

void input()
{
for (int i = 0; i < n; i++)
scanf("%lf%d", &rider[i].s, &rider[i].t);
}

int main()
{
// freopen("t.txt", "r", stdin);
while (scanf("%d", &n), n)
{
input();
sort(rider, rider + n);
int i = 0;
while (rider[i].t < 0)
i++;
printf("%.0f\n", ceil(rider[i].t + length * 3.6/ rider[i].s));
}
return 0;
}