neal's blog

By neal, 5 years ago, In English

When trying to generate some of my own test cases for 1190E - Tokitsukaze and Explosion, I noticed that it was hard to make cases where even slightly large values of $$$m$$$ didn't all give the same answer. After some thinking this makes perfect sense, because with larger values of $$$m$$$, points that are very far away from the origin become almost freebies; only the few closest points to the origin should really matter.

So on a whim, I tried submitting some 'incorrect' code to the problem. After several rounds of experimentation (in other words, even more binary search), I found that you can add this line to your code:

M = min(M, 4);

and still get accepted. Turns out you don't need all the $$$2^k$$$ jump pointers which were mentioned in the editorial; you can just iterate each element four times instead. ;)

I'll try to generate some stronger test cases. Should be a good chance to try out the new uphacking feature.

EDIT: I generated three strong cases with M = 18, M = 200, and M = 1025 ("strong" meaning that increasing M further still changes the answer). They're now all in the system tests. You'll notice them if you get WA on test 149 or later.

  • Vote: I like it
  • +218
  • Vote: I do not like it

| Write comment?
»
5 years ago, # |
  Vote: I like it -29 Vote: I do not like it

Time to use uphacking feature