A lottery function (customized number and probability of winning prizes)

Suitable for lottery system

/*
 * A lottery category, accurate to one ten thousandth
 * Three steps: 1. Accept a winning probability array; 2. Accept a lottery seed; 3. Return the winning level
 * /

class Lottery {
 /*
 * Winning probability array, automatically determine the number of awards
 * The sum of the array key values ​​is 100, automatically calculate the probability of not winning, if the initial value exceeds 100, an error will be thrown
 */

 protected $_rate = array();

 /*
 * Set the winning probability,
 * @param Array, the winning probability, passed in as an array
 */

 public function setRate($rate = array(12.1, 34) ) {
 $this->_rate = $rate;
 if (array_sum($this->_rate) > 100)//Detect whether there is a problem with the probability setting
 throw new Exception('Winning rate upto 100%') ;
 if (array_sum($this->_rate)  //Define the probability of not winning. When the probability given by the user only sums to 100, ignore 0
 $this->_rate[] = 100 - array_sum($this->_rate);
 }

 /*
 * Randomly generate an integer seed from 1 to 10000 and submit it to the winning judgment function
 * @return int, sorted by the incoming probability, return the winning The number of items
 */

 public function runOnce() {
 return $this->judge(mt_rand(0, 10000));
 }

 /*
 * According to the set probability, judge an incoming Whether the random value wins the prize
 * @param int,$seed Random number within 10000
 * @return int,$i Sort by the passed probability and return the number of winning items
 */

 protected function judge($seed) {
 foreach ($this->_rate as $key => $value) {
 $tmpArr[$key + 1] = $value * 100;
 }
 //Multiply the probability by ten and accumulate it for random selection, Combined into
 $tmpArr[0] = 0;
 foreach ($tmpArr as $key => $value) {
 if ($key > 0) {
 $tmpArr[$key] += $tmpArr[$key - 1];
 }
 }
 for ($i = 1; $i  if ($tmpArr[$i - 1]  return $i; //Return the number of winning items (in order of setting probability)
 }
 }
 }

}

$rate = array(33, 20, 2, 0.95, 12, 4.55);

$a = new Lottery;
$a->setRate($rate);
for ($i = 0; $i  $b = $a->runOnce();
 @$rewards[$b]++;
}
unset($rewards['']);
echo array_sum($rewards);
?>





  < ;thead>Run 10,000 times, compare the set probability and the number of winnings  > ;       


Set the probability
The number of winnings
 


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