We may assume that all the students except "Charley" ride from Wanliu to Yanyuan at a fixed speed. Charley is a student with a different riding habit - he always tries to follow another rider to avoid riding alone. When Charley gets to the gate of Wanliu, he will look for someone who is setting off to Yanyuan. If he finds someone, he will follow that rider, or if not, he will wait for someone to follow. On the way from Wanliu to Yanyuan, at any time if a faster student surpassed Charley, he will leave the rider he is following and speed up to follow the faster one.

We assume the time that Charley gets to the gate of Wanliu is zero. Given the set off time and speed of the other students, your task is to give the time when Charley arrives at Yanyuan.

Vi [TAB] Ti

Vi is a positive integer <= 40, indicating the speed of the i-th rider (kph, kilometers per hour). Ti is the set off time of the i-th rider, which is an integer and counted in seconds. In any case it is assured that there always exists a nonnegative Ti.

题解：贪心

代码：

#include <bits/stdc++.h>

using namespace std;

#define inf 0x3f3f3f3f

int n;

struct Node {

    int v;

    int t;

    int need;

}node[10000];

int main(){

    while(~scanf("%d", &n)){

        if(!n) break;

        for(int i = 0; i < n; i ++)

            scanf("%d%d", &node[i].v, &node[i].t);

        for(int i = 0; i < n; i ++){

            if(node[i].t < 0) {

                node[i].need = inf;

            } else{

                node[i].need = (int)((4500 * 3.6) / node[i].v + node[i].t);

                if((int)(4500 * 3.6) % node[i].v)

                    node[i].need ++;

            }

        }

        int ans = node[0].need;

        for(int i = 1; i < n; i ++)

            ans = min(ans, node[i].need);

        printf("%d\n", ans);

    }

    return 0;

}