Could someone tell me how to sovle this task

task name : explosion

And this is my submit
http://www.z-trening.com/submit.php?subm_stat=1&submit=7100245082

It's accept 8/10

I couldn't understand.

First I sort them by their x-position.
Then, I just want to find each can reach right-most and left-most and check the answer.
Is it right?

In 10th test case there missed 1 number, don't know since when. I haven't changed test cases, so I really don't know what happened.

Oh!

But I have put rand function in my code

I first time submit my code and pasted it
it seems I am very lucky

and I have saw an right code ,

and I have know where I am wrong

thanks