Does anyone knows how to solve this problem ? http://cepc08.ii.uni.wroc.pl/cards.pdf
I've been trying to solve this problem, got some ideas but none of those ideas has really worked. Can anyone give me a hint ?
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Соревнования по программированию 2.0
Время на сервере: 23.12.2024 08:43:52 (f1).
Десктопная версия, переключиться на мобильную.
При поддержке
YES is when exist such k, l, n, m ≥ 0 so
c = k × a + l × b
d = m × a + n × b.
NO otherwise.
What's the proof ? I could see this approach, but I wasn't sure if this is right.
counter-example:
c=3 d=7 a=2 b=3
c=0a+1b
d=2a+1b
Yep, one more condition: a × b must divide c × d
UPD This seems to be legit, but in paper I found another: (c = q × a or d = q × a) and (c = w × b or d = w × b).
Can you prove it ?
That paper in russian. Sorry, I'm in lack of time to translate it.