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9 random digits (Posted on 2003-05-02) Difficulty: 3 of 5
Suppose you want to make a random 9 digit number, using every number from 1 to 9 exactly once. You have a process called random(top) that gives a random number up to top (if top was 5, it would give random numbers from 1 to 5)

a) How could you do this?

b) If top couldn't be more than 9, how could you do this using random(top) only 9 times (or less)?

See The Solution Submitted by Gamer    
Rating: 3.4000 (5 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution Solution | Comment 16 of 20 |
for i = 9 down to 1,
set array[i] to i
for i = 9 down to 1,
swap array[i] with array[random(i)]

  Posted by Federico Kereki on 2003-07-14 15:35:14
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