With regard to this time’s Long Challenge and the question Highway crossing.
I feel that I have got my logic on point but seem to be missing some minute detail. I pass all the tests except the second subtask’s second part. I feel my code is almost self explanatory.
I’ve gone over my code about 20 times but can’t see what I’m missing!
I’ve solved taking normal X,Y axis with cars moving on X axis and Chef going downwards in negative Y direction hence the coordinates.
The submission link as well - https://www.codechef.com/viewsolution/18214679
Thanks In Advance 
#include <iostream>
#include<stdio.h>
#include<bits/stdc++.h>
#define ll long long int
#define li long int
using namespace std;
int main()
{
ios::sync_with_stdio(0);
ll t;
cin>>t;
while(t--)
{
//double g=-10000000000.12432;
//cout<<setprecision(16)<<g;
ll n,s,y;
cin>>n>>s>>y;
double time_to_cross_lane=double(y)/double(s);
vector<ll> velocities(n);
vector<ll>directions(n);
vector<ll>positions(n);
vector<ll>lengths(n);
for(ll i=0;i<n;i++)
{
cin>>velocities[i] ;
}
for(ll i=0;i<n;i++)
{
cin>>directions[i] ;
}
for(ll i=0;i<n;i++)
{
cin>>positions[i] ;
}
for(ll i=0;i<n;i++)
{
cin>>lengths[i] ;
}
double total_time=0.0;
for(ll i=0;i<n;i++)
{
//left to right
if(directions[i]==1)
{
// coordinates of car. left and right at any time
double left_coordinate =(positions[i]-lengths[i])+velocities[i]*(total_time);
double right_coordinate =(positions[i] )+velocities[i]*(total_time);
// case 1 not hitting
if(left_coordinate>=0 && right_coordinate>=0)
{
total_time+=time_to_cross_lane;
continue;
}
//case 2
else if(left_coordinate<=0 && right_coordinate>=0)
{
total_time+=(double(-left_coordinate)/double(velocities[i])) + time_to_cross_lane;
continue;
}
//case 3
else if(left_coordinate<=0 && right_coordinate<=0)
{
double time_to_reach_for_car=(double(-right_coordinate)/double(velocities[i]));
double time_to_cross_length = double(lengths[i])/double(velocities[i]);
// if car reaches before chef would cross the lane
if( time_to_reach_for_car<=time_to_cross_lane)
{
total_time+=time_to_reach_for_car+time_to_cross_length+time_to_cross_lane;
}
else
total_time+=time_to_cross_lane;
}
// if a coordinate is zero
else if( left_coordinate==0 || right_coordinate ==0 )
{
if(left_coordinate==0)
{
total_time+=time_to_cross_lane;
}
else if(right_coordinate==0)
{
total_time+=time_to_cross_lane+(double(lengths[i])/double(velocities[i]));
}
}
else
total_time+=time_to_cross_lane;
}
//right to left
else if(directions[i]==0)
{
double left_coordinate =(positions[i])-(velocities[i]*total_time);
double right_coordinate =(positions[i]+lengths[i])-(velocities[i]*total_time);
// case 1 not hitting
if(left_coordinate<=0 && right_coordinate<=0)
{
total_time+=(time_to_cross_lane);
}
else if(left_coordinate<=0 && right_coordinate>=0)
{
total_time+=(double(right_coordinate)/double(velocities[i]) + time_to_cross_lane);
}
else if(left_coordinate>=0 && right_coordinate>=0)
{
double time_to_reach_for_car=(double(left_coordinate)/double(velocities[i]));
double time_to_pass =(time_to_reach_for_car+( double(lengths[i])/double(velocities[i])));
//car would reach before chef would cross lane
if( time_to_reach_for_car<=time_to_cross_lane)
{
total_time+=(time_to_pass+time_to_cross_lane);
}
else
total_time+=(time_to_cross_lane);
}
//coordinate is zero
else if(left_coordinate==0||right_coordinate==0)
{
if(left_coordinate==0)
{
total_time+=(time_to_cross_lane+( double(lengths[i])/double(velocities[i])));
}
else if(right_coordinate==0)
{
total_time+=(time_to_cross_lane);
}
}
}
}
cout<<fixed<<setprecision(12)<<total_time<<'\n';
}
return 0;
}