There is a small error in the code above in the tgtId CTE. The fl.low will not always match fl.high. Changing the WHERE clause to the following should fix that...

Thank you VERY MUCH for this article! I have already used the algorithm to greatly improve the performance of a poorly written query (from another developer).

Interestingly, this developer needed to...

Would someone please provide a brief explanation as to why these solutions work? Is it just simple recursion?