Shuffle

[Bill Baxter]

BCS wrote:
> Oskar Linde wrote:
>> Walter Bright wrote:
>>
>>>     /* Shuffle the files[] array
>>>      */
>>
>>
>> To be nitpicky, your algorithm will not give a perfect shuffling. 
>> Consider shuffling the sequence 012. The algorithm has 3^3 = 27 
>> different ways it can shuffle the sequence, and there exists 3! = 6 
>> different permutations of the sequence. Since 27 isn't divisible by 6, 
>> the algorithm will give a slight bias towards some end sequences. 
>> (021,102 and 120 in this case). A quick fix is to change the first 
>> line of the loop body:
>>
> 
> What would you get if you qsorted the list with rand used as the compare 
> function?

At best, an O(N log N) shuffle instead of O(N).

--bb