After just missing advancing out of Google Code Jam Round 1A, I tried again in Round 1B and again in Round 1C, but with no success. I guess I haven’t adapted well to the new interactive problems. In both cases, I got the first problem solved and then got stuck on the second problem, which was interactive in both cases. The interactive problems require your submission exchange messages with another program to work out the solution, which makes it a bit different to debug.
In the interest of advancing, I should have moved on to the third problem or just did the easier subset of the interactive problem. But I’m only doing this for the fun of the challenge, and it was fun to eventually work out the solution, even though it took me a little longer than the allotted time.