I'm trying to find 2 squares in a collection of squares that overlap.
Here's the segment of my code that's buggy: https://hatebin.com/apaolkatzj
`relevant` is a `set`, and `IDSquare` is just a custom class. `overlapping` is a `vector` of `pair`s. However, sometimes the `upper` iterator seems to be returning an element that isn't in the set at all. I'm particularly baffled by this because I did perform a check for if `prescence` was at the end already.
Am I missing something? Any help would be appreciated!