Hello!
I've seen a couple of problems where the intended solution is to use Hall's Marriage Theorem on some weird reduction to solve the problem. These are few and hard to find, so I wanted to ask you for any problems/learning materials regarding this theorem.
One example is IOI-2015/Day1/Teams (although the reduction is fairly natural).
Thank you in advance








ARC076F — Exhausted
Thank you
https://www.acmicpc.net/problem/8177
Ice skates is the classic example I know and a really good problem imo
Thank you
628F - Bear and Fair Set
Thank you
I authored one more Hall's Theorem problem: 611H - New Year and Forgotten Tree.
Thank you
106016J - Arranged Marriage
Thank you
iirc candies from this year's NOI in Bulgaria uses Hall's theorem.
Thank you
Yet another Hall's theorem problem.
Thank you
JOI Spring Camp Ants and Sugar (sorry on the phone no link)
Thank you
I think this is the link for anyone interested
https://qoj.ac/problem/6339
Not Hall's Theorem itself, but a similar idea
Thank you
Not sure if it is something on my behalf, but it seems you need to be logged in to see the problem
https://mirror.codeforces.com/gym/106017/problem/M I haven't coded the solution but my ideas for this problem all come from Hall's theorem.
Thank you
this is actually from SEERC 2023 105465I - Impossible Numbers
prins could you please put some notes in your contest to give credits to the original authors?
I added an announcement about this, the rest of the problems are original.
Everything listed here;
search query on solved.ac
Thank you