CODEWITHSUNDEEP
phprandom
user3299251
user3299251

Reputation: 108

Generate 15 random numbers that may be the same 2 times but not 3 times

I am working on a scratch card in PHP and i need to build the backbone behind it.

My plan is as following:

  1. Generate 15 random numbers ( there are 8 containers and 15 images to choose from. ).

  2. Each number correspondences with a image ( 1 is image 1, 2 is image 2 etc. ).

  3. Show a random image (1/15) on container 1, show random image (1/15) on container 2 etc. There are 8 containers to be filled.

What i currently can't figure out is to check if there are duplicate numbers, and if so it is fine to have 2 duplicates but not 3 since that would mean a win.

What i have now is this:

$images = array();
for ($i = 0; $i < 8; $i++) {
    $random[$i] = rand(1,15);
}

This will fill $random with 15 numbers i can use. Now i want to check if within those 15 there are duplicates. But the trick is that duplicates are no problem ( and even preferred on some degree ) but once there are 3 of the same numbers i want one of those to change again in a random number ( and re-check for duplicates).

So what should be fine ( 2x 8 is fine, 2x 1 is fine ):

Container 1: 14
Container 2: 8
Container 3: 8
Container 4: 4
Container 5: 1
Container 6: 9
Container 7: 1
Container 8: 12

What should be incorrect ( 3x 14 is not fine ):

Container 1: 14
Container 2: 8
Container 3: 4
Container 4: 14
Container 5: 14
Container 6: 9
Container 7: 1
Container 8: 12

You guys have any advice on what the right way is here? I am trying to stay away from a lot of "if's".

Upvotes: 0

Views: 191

Answers (2)

Andreas
Andreas

Reputation: 23958

Two sets of 15 ranges and shuffle them.
Then slice out 8 items from the array.

$random = array_merge(range(1,15), range(1,15));
shuffle($random);

$random = array_slice($random, 1,8);
Print_r($random);

Upvotes: 1

MC Emperor
MC Emperor

Reputation: 22997

You could create an array with each selectable element twice.

Then, 8 times, pick a random index from the array and remove it from the array.

$random = [ ];
for ($i = 1; $i <= 15; $i++) {
    $random[] = $i;
    $random[] = $i; // Twice
}

for ($i = 0; $i < 8; $i++) {
    $pick = rand(0, count($random));
    // Use $random[$pick]
    // Remove array key at index $pick
}

Upvotes: 0

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