# Help me in solving PTRLP problem

### My issue

I havent understood what the problem is asking me to do…on what basis is the starting point being chosen? we dont have the maximum amount of money which can be spent

### My code

``````#include <iostream>
using namespace std;

int main() {
int t; cin>>t ;
while(t--){
long long n ;
cin>>n ;
long long petrol[n], cost[n] ;
for(int i = 0 ; i<n ; i++){
cin>>petrol[i] ;
}

for(int i = 0 ; i<n ; i++){
cin>>cost[i] ;
}
}
return 0;
}

``````

Problem Link: CodeChef: Practical coding for everyone

The question states that to go from ith to (i+1)th station it require cost[i] petrol and petrol available at ith station is p[i] .
So u can only complete the trip when around the trip the sum of p[i]>=cost[i] else u can’t complete the trip .
I have coded the same intuition hope u will get it.

``````#include <iostream>
using namespace std;

int main() {
int n;
cin>>n;
int a[n],b[n];
int ans=-1;
for(int i=0;i<n;i++)
{
cin>>a[i];
}
for(int i=0;i<n;i++)
{
cin>>b[i];
}
for(int i=0;i<n;i++)
{
if(a[i]>=b[i])
{
int sma=a[i];
int smb=b[i];
int j=(i+1)%n;
int ch=0;
while(j!=i)
{
sma+=a[j];
smb+=b[j];
if(sma<smb)
{
ch=1;
break;
}
j=(j+1)%n;
}
if(ch==1)
{
if(j<i)
{
break;
}
i=j;
}
else
{
ans=i;
break;
}
}
}
cout<<ans;
return 0;
}
``````
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