>>13566701I feel you anon, I really enjoy inclusion exclusion problems. One of my Discrete Math final problems was this:
>You have 14 treasure chests, and 4 islands. You can place treasure chests in islands according to any ordering you wish, so for example you could have all 5 chests mapped to 1 island, all 5 chests mapped to no island, or anything in between. How many mappings are there of chests to islands, such that island 1 has no more than 2 chests, island 2 no more than 4, island 3, no more than 5, and island 4 no more than 6.I never knew how to solve these problems before, but once you know how unions work at a basic level, then you just need to find obviously the set of every solution, and subtract the union of all the sets containing properties such that island 1 has more than 2, island 2 more than 4, etc.... Once you know how that works its really easy. It's honestly an incredibly powerful tool.
