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  1. <?php
  2.  
  3. // your code goes here
  4. function randomFactory(array $data): Closure {
  5.     $values = [];
  6.     $rand = 0;
  7.     foreach ($data as $value => $chance) {
  8.         $values[] = [
  9.             'rand' => $rand += $chance,
  10.             'value' => $value,
  11.         ];
  12.     }
  13.  
  14.     return function () use ($values) {
  15.         $rand = random_int(0, PHP_INT_MAX) / PHP_INT_MAX;
  16.         foreach ($values as $value) {
  17.             if ($rand < $value['rand']) {
  18.                 return $value['value'];
  19.             }
  20.         }
  21.  
  22.         throw new LogicException('smth get wrong');
  23.     };
  24. }
  25.  
  26. $data = [
  27.     1 => 0.1,
  28.     2 => 0.25,
  29.     3 => 0.25,
  30.     4 => 0.4,
  31. ];
  32. $random = randomFactory($data);
  33.  
  34. $result = array_combine(array_keys($data), array_fill(0, count($data), 0));
  35. $attempts = 10000;
  36. for ($i = 0; $i < $attempts; ++$i) {
  37.     $rand = $random();
  38.     ++$result[$rand];
  39. }
  40.  
  41. echo "value\tcount\texpected\treal\tdiff", PHP_EOL, PHP_EOL;
  42. foreach ($result as $value => $count) {
  43.     $real = $count / $attempts;
  44.     $diff = abs($real - $data[$value]);
  45.     printf("%d\t%5d\t%8.2f\t%.2f\t%.2f" . PHP_EOL, $value, $count, $data[$value], $real, $diff);
  46. }
Success #stdin #stdout 0.06s 23596KB
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stdin
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Standard input is empty
stdout
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value	count	expected	real	diff

1	  999	    0.10	0.10	0.00
2	 2474	    0.25	0.25	0.00
3	 2569	    0.25	0.26	0.01
4	 3958	    0.40	0.40	0.00
https://ideone.com/687fQ6
language:
PHP (php 7.3.5)
created:
5 years ago
visibility:
public

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