CONPOIN - Editorial

@shivamg_isc

Check this :-- http://www.codechef.com/viewsolution/7234731

I just changed your soln a little bit…

All >= signs are there as it is except for n = 5 (last case) as 5C2 is 10…

That was your mistake for n = 5 and m = 9 ans is 1 and for n = 5 and m = 10 ans must be 0…

Hope you can understand…

@shivamg_isc , agree with you.
As the problem statement says the given m edges are non-intersecting.
For n=5, and the optimal planar graph will have 9 edges (i.e. we cannot add more edge). Since they are not giving non-intersecting edges they cannot give m>=10 for n=5, so for m<9 answer should be 0 and m>=9 answer should be 1. But it gave me wrong answer. I got correct answer for 20 points when i did m==9 instead of m>=9. Why so, if they haven’t given m>=10 (because for m>=10 the m edges will intersect) ???
I mean answer should not depend for m>=10 for n=5 since they are not giving non-intersecting edges.
Am i wrong anywhere in understanding anything??

@checkmate1 , Yes 5C2 is 10.But they cannot give m=10 for n=5 because for this the edges will intersect but question say the given m edges are non-intersecting. So how they can give m=10 non-intersecting edges for n=5??? So one cannot say whats the answer for m=10 and n=5.

@shubham201
that is what… this is exactly the point which flashed in my mind. It is impossible for them to give m=10 for n=5. Was there some problem with the test cases ? :confused:
This question sucks .

Editorials are supposed to provide an opportunity for us to learn. Not point to a third party link! Wake up guys!

Case n=5, m=10 the answer is 0 while you are printing 1.

Uploaded the paper (PDF) here: https://www.scribd.com/doc/269955060/A-simple-recognition-of-maximal-planar-graphs

Again, you are stressing the wrong words.

“If you choose points in ANY WAY, and they ALWAYS fit the conditions stated (regardless of what points you chose)”

IT DOES NOT SAY IF YOU CHOOSE. IT SAYS IS IT POSSIBLE TO CHOOSE.

If you want to consider ALL POSSIBLE SETS OF POINTS, then you CANNOT use the phrase “IS IT POSSIBLE TO CHOOSE”! You must say “among all possible sets of points”.

Both IS IT POSSIBLE and TO CHOSE make your argument wrong. IS IT POSSIBLE ALWAYS means is there at least one case which is true, NOT is there at least one case which is false.

Please read this carefully.