PHP probability algorithm examples suitable for lottery programs and random advertisements_PHP tutorial

if (!isset($arr[$key])) {
$max = array_sum($ps);
foreach ($ps as $k=>$v) {
$ v = $v / $max * 10000;
for ($i=0; $i<$v; $i++) $arr[$key][] = $k;
}
}
Return $arr[$key][mt_rand(0,count($arr[$key])-1)];
}

//Total probability accuracy of probability array
$proSum = array_sum($proArr);

//Probability array loop
foreach ($proArr as $key => $proCur) {
$randNum = mt_rand(1, $proSum);
if ($randNum <= $ proCur) {
                $result = $key;                                             🎜> unset ($proArr);

Return $result;
}

The above code is a classic probability algorithm. $proArr is a preset array. Assume that the array is: array(100,200,300,400), starting from 1 , within the probability range of 1000, screen whether the first number is within its occurrence probability range. If not, the probability is reduced, that is, the value of k minus the probability space of the number just now, in this case Subtract 100, which means that the second number is filtered within the range of 1,900. In this way, until the end, there will always be a number that meets the requirements. It's like touching something in a box. If the first one isn't there, the second one isn't there, and the third one isn't there, then the last one must be. This algorithm is simple and very efficient. The key is that this algorithm has been applied in our previous projects, especially in projects with large amounts of data. The efficiency is very good.
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