I was not implying anything beyond what I clearly stated, specifically, that your suggestion was wrong and misleading. Arguably, if you don't know how to sort, you are an incompetent programmer, but that's besides the point. Your trouble with A* had nothing to do with stable sorting or with the sort returning a different result every time. That's obviously unlikely if you pass it the same input. It had to do with you failing to read the documentation that describes what your callback should do.