problem link:https://www.codechef.com/problems/MSTICK

solution link:https://www.codechef.com/viewsolution/16520062

It is a basic segment tree problem with an insight.

## Click to view

First thing, calculate min (L,R), This is the time fire reached joint end.

Calculate max((0, L-1), (R+1, N-1)). This is the time fire will take from joint end to reach tip of matchsticks which were not ignited.

calculate ceil( (max(L,R) - min(L,R))/2). This is the time for all matchsticks within range L to R to be ignited completely, after fire reaching joint end.

Now, answer will be min(L+R) + max( max(0, L-1), max(R+1, N-1), ceil( (max(L,R) - min(L,R))/2)).

Now, Implementing it is a simple implementation of Segment tree.

this is exactly what I have done.

it would be helpful if you could point out the mistake in my code

i guess you should use ceil function for ceil( (max(L,R) - min(L,R))/2)

Also, refer this implementation of Segment tree for min-max queries

but i did max((max(l,r)+min(l,r))/2,min(l,r)+max( max(0, L-1), max(R+1, N-1)))

which is basically the same thing and hence does not require ceil function

Wait…

I’m solving it myself…

it would be nice if u could point out error in my code,instead of solving it your self:)

Your segment tree is working fine…

Can’t figure out what’s wrong with your code…

My code with same approach gives AC

Its simple. Use double not float because you need precision for values as large as {2}*{10}^{8}.

See this TC-

```
Input
5
100000000 100000000 100000000 100000000 99999999
1
2 4
Your Output
200000000.0
Correct Output
199999999.0
```

Determining what data type to use is the most fundamental concept which requires 100% accuracy. Be careful next time.

Also, next time, please give 2 minutes into indenting your code or adding proper comments. Its really painful for eyes to see an un-indented and uncommented code. Please think of the person going through your code to help you.

thanks a lot!!

And I definitely will try to indend my code from next time…

thanks for your help…

found the solution to my problem

Thank you dear