水题：HDU 5112 A Curious Matt

 1 #include <algorithm>
 2 #include <iostream>
 3 #include <cstring>
 4 #include <cstdio>
 5 #include <cmath>
 6 using namespace std;
 7 const int N=1000010;
 8 int tim[N],pos[N],p[N];
 9 bool cmp(int x,int y){
10     return tim[x]<tim[y];
11 }
12 int main(){
13     int T,n,cas=0;
14     double ans;
15     scanf("%d",&T);
16     while(T--){
17         scanf("%d",&n);
18         for(int i=1;i<=n;i++){
19             scanf("%d%d",&tim[i],&pos[i]);
20             p[i]=i;
21         }
22         sort(p+1,p+n+1,cmp);
23         ans=0.0;
24         for(int i=2;i<=n;i++)
25             ans=max(ans,fabs(pos[p[i]]-pos[p[i-1]])/fabs(tim[p[i]]-tim[p[i-1]]));
26         printf("Case #%d: %.2f\n",++cas,ans);
27     }
28     return 0;
29 }