Re: [racket-users] do loops

2016-02-15 Thread JJ
> it only requires O(log n) on a (balanced) search tree: sorry, O(log n) for conttains? and O(n log n) in total -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to

Re: [racket-users] do loops

2016-02-15 Thread JJ
Right, but evaluating tree-size is O(n), even with a binary search tree. Doing this on each insertion is slow. The following is a possible solution without "do", and it only requires O(log n) on a (balanced) search tree: (define tree5 (let loop ([tree null] [n 5]) (define x (random 10))

Re: [racket-users] do loops

2016-02-15 Thread Robby Findler
Or if you know that there are only 10 candidates, you can just iterate over (a prefix of) this list: (shuffle (build-list 10 values)) Robby On Mon, Feb 15, 2016 at 8:37 AM, Tony Garnock-Jones wrote: > If your "insert" is idempotent, and you have some means of measuring > tree size, you can el

Re: [racket-users] do loops

2016-02-15 Thread Tony Garnock-Jones
If your "insert" is idempotent, and you have some means of measuring tree size, you can eliminate i, c and x: (define tree4 (do ([tree null (insert tree (random 10))]) [(>= (tree-size tree) 5) tree])) I arrived at this by considering doing something similar for sets: (define tree4 (do ([

[racket-users] do loops

2016-02-14 Thread JJ
I try to fill a binary tree with 5 random numbers, avoiding duplicates. Is there a more elegant way than this (using "Iterations and Comprehensions")? (define tree4 (do ([x (random 10) (random 10)] [c #f (contains? tree x)] [tree null (if c tree (insert tree x))] [i 0 (if c