codeforces 782B - The Meeting Place Cannot Be Changed

time limit per test
5 seconds

memory limit per test
256 megabytes

input
standard input

output
standard output

The main road in Bytecity is a straight line from south to north. Conveniently, there are coordinates measured in meters from the southernmost building in north direction.

At some points on the road there are n friends, and i-th
of them is standing at the point xi meters
and can move with any speed no greater than vi meters
per second in any of the two directions along the road: south or north.

You are to compute the minimum time needed to gather all the n friends at some point on the road. Note that the point they meet at
doesn't need to have integer coordinate.

Input

The first line contains single integer n (2 ≤ n ≤ 60 000) —
the number of friends.

The second line contains n integers x1, x2, ..., xn (1 ≤ xi ≤ 109) —
the current coordinates of the friends, in meters.

The third line contains n integers v1, v2, ..., vn (1 ≤ vi ≤ 109) —
the maximum speeds of the friends, in meters per second.

Output

Print the minimum time (in seconds) needed for all the n friends to meet at some point on the road.

Your answer will be considered correct, if its absolute or relative error isn't greater than 10 - 6.
Formally, let your answer be a, while jury's answer be b.
Your answer will be considered correct if 

 holds.

Examples

input

3
7 1 3
1 2 1

output

2.000000000000

input

4
5 10 3 2
2 3 2 4

output

1.400000000000

#include<cstdio>
struct type{
int
a6ae
x;
int v;
}p[60000+5];
int n;
bool check(double time)
{
//遍历每个人在time个单位时间后能走到的位置，不断更新重叠的区间[l,r]，只要到最后这个区间一人不为空，就return true
double l=p[1].x-time*p[1].v;
double r=p[1].x+time*p[1].v;
for(int i=2;i<=n;i++){
if(p[i].x-time*p[i].v > l) l=p[i].x-time*p[i].v;
if(p[i].x+time*p[i].v < r) r=p[i].x+time*p[i].v;
if(l>r) return false;
}
return true;
}
int main()
{
scanf("%d",&n);
for(int i=1;i<=n;i++) scanf("%d",&p[i].x);
for(int i=1;i<=n;i++) scanf("%d",&p[i].v);
double st=0,ed=1000000000;
while(ed-st>1e-7){
double mid=st+(ed-st)/2;
if(check(mid)) ed=mid;
else st=mid;
}
printf("%.12lf\n",ed);
}