Not trying to be that guy, but again, these photographers broke the rules. These photos were not taken within the week of the contest.
3rd place: The picture was posted with immediately within 24 hours of the original contest post. This is within the rules, but very interesting... also the meta-data from the photos has been conveniently stripped, so it doesn't show the dates. Also, the user has no previous social media, and is using a vast assortment of photos across a ton of different contest, which makes me think these are backlogged. However, no evidence, and it's the closest to the rules.
2nd place: Took his photos before the contest by 2 days, and then posted them. Sorry, but that still is not within the rules. The meta data in the photo shows this. You can tell it's the meta from his photo, as it has the same name as his user account.
1st Place: Also broke the rules. Taking the meta data from the same shot he posted on his website, we can see the photo was created 9 days ago, at least a 1.5 days before the contest start.
Again, you need to have people take a shot of them with some sort of proof of them TAKING the shot DURING the allotted week. Not sure how you would incorporate this, but otherwise people are competing with others that are winning, but breaking the rules.