I've been solving the puzzles on http://adventofcode.com/ in Scala. Here are my solutions.
I've been using IntelliJ IDEA with the Scala plugin and Scala Worksheets. By default, IntelliJ runs the worksheets in the NailgunRunner process that also does the compilation. A couple solutions take more than the default allotted memory. In IDEA you can up the JVM maximum heap size in Preferences, Scala Compile Server.
You can find a big treasure trove of information on the puzzles and the solutions on https://www.reddit.com/r/adventofcode/