I have the feeling that searching forward or backward won't result in a well shuffled result; I'd think you'd tend to end up with some ranges of numbers clumping toward the end and some toward the beginning. Just a feeling, though...

One alternative is to do random selection (repeating until successful) for the first X percent of N, then switching to scanning through the whole bitmap until you find the rand(number-remaining)'th remaining number. Some benchmarks would be needed to pick a good X; I'd guess 90%.

In reply to Re: Generating 0 .. N Randomly and Efficiently by ysth
in thread Generating 0 .. N Randomly and Efficiently by Limbic~Region

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