Copyright (C) 2020-2021 Terence Kelly. All rights reserved. Author contact: tpkelly@acm.org, tpkelly@eecs.umich.edu, tpkelly@cs.princeton.edu Addenda and/or errata to the source code supplied herewith will be posted in association with my "Drill Bits" column on clearing auctions in ACM _Queue_ magazine circa late 2020 / early 2021. If the column is re-published in _Communications of the ACM_, that might become the definitive home of addenda, errata, etc. Check both. Another (possibly less permanent) place to find follow-on material is my Web site: http://web.eecs.umich.edu/~tpkelly/Drill_Bits/ The source code has been compiled with GCC and tested on Linux. It is intended to be portable to other compilers and OSes without excessive fuss. Re-format to taste with the "indent" utility. I recommend compiling with GCC's "-fsanitize=undefined" flag if your version of GCC supports it. That should catch out-of-bounds array subscripts and signed integer overflow errors at run time. Program "rb" generates random bids. Program "auclear" clears two-resource auctions. Script "run.csh" compiles and runs both programs.