# Gavin Andresen
# 2011-10-18 13:29:29
# https://bitcointalk.org/index.php?topic=48832.msg581044#msg581044

What are you optimizing for?  Ease of implementation? Wallet size? @p{par}

Here's a naive implementation that I bet would work well in practice: @p{par}

+ Sort potential inputs by priority (priority is #confirmations * amount) @p{par}

+ Use the N highest-priority coins whose sum @s{gt}= amount needed @p{par}

If you want to optimize for fragmentation and/or paying of fees, then also do: @p{par}

+ If the change transaction is larger than some threshold amount, then split it in half (or maybe split it into Y change outputs, each of which is about the size of the threshold amount). @p{par}

+ If the change transaction is small and there are other small-valued/low-priority inputs available, add a few small-value inputs to merge them together. @p{par}

You could also optimize for privacy (try to avoid using more than one input and/or always create multiple change outputs), or tweak the above rules to try to always avoid fees... @p{brk}