Two papers by kit1980 and me:

• Declaratively solving tricky Google Code Jam problems with Prolog-based ECLiPSe CLP system, The 30th ACM/SIGAPP Symposium On Applied Computing (preprint: http://arxiv.org/abs/1412.2304)
• Declaratively solving Google Code Jam problems with Picat, Practical Aspects of Declarative Languages 2015 (preprint: http://arxiv.org/abs/1504.00977)

And for a lighter reading, Cognitive Biases in Competitive Programming :-)