PHP probabilistic algorithm (RPM)

Cases:
function Get_rand ($PROARR) {     $result = ';     The total probability accuracy of the probability array    $proSum = Array_sum ($PROARR);     Probability array Loop    foreach ($proArr as $key + = $proCur) {         $randNum = Mt_rand (1, $proSum);         if ($randNum <= $proCur) {             $result = $key;             break;         } else {             $proSum-= $proCur;         }     }     Unset ($PROARR);     return $result; }

$prize _arr is a two-dimensional array that records all of the prize information for this draw, where the ID indicates the winning grade, prize represents the prize, and V indicates the probability of winning. Note that the V must be an integer, and you can set the V of the corresponding prize to 0, meaning that the odds of the prize being pumped are 0, the sum of V in the array (cardinality), and the larger the cardinality, the more accurate the probability. In this case, the sum of V is 100, then the winning probability of the tablet computer is 1%, if the sum of V is 10000, then the probability of winning is one out of 10,000.

$prize _arr = Array (' 0 ' = = Array ('     id ' =>1, ' prize ' = ' computer ', ' V ' =>1),     ' 1 ' = = Array (' ID ' =>2, ' Prize ' + ' camera ', ' V ' =>5),     ' 2 ' = = Array (' ID ' =>3, ' prize ' = ' Speaker ', ' V ' =>10),     ' 3 ' = = Array (' id ' = >4, ' prize ' = ' USB ', ' V ' =>12, '     4 ' = = Array (' ID ' =>5, ' prize ' = ' Q ', ' V ' =>22),     ' 5 ' = Array (' ID ' =>6, ' prize ' = ' refueling ', ' V ' =>50),);  

Every time a front-end page is requested, the PHP loop prizes are set in an array, using the probability calculation function Get_rand to get the prize ID in the drawing. Save the winning prize in the array $res[' yes ', and the remaining non-winning information is saved in $res[' no ', and finally output JSON data to the front page.

If the winning data is placed in the database, it is necessary to determine the number of winning//in the 1, 2, 3 and other prizes, if the maximum number of unset corresponding awards, avoid repeating the jackpot//code here Eg:unset ($prize _arr[' 0 ') foreach ($prize _arr as $key + $val) {     $arr [$val [' id ']] = $val [' V '];} $rid = Get_rand ($arr);//probability of obtaining the prize id$res[' Yes '] = $prize _arr[$rid -1][' Prize '); In the awards//will be excluded from the array, the remaining awards, if the database validation, here can be omitted unset ($prize _arr[$rid-1]); Shuffle ($prize _arr); Scrambled array order for ($i =0; $i <count ($prize _arr); $i + +) {     $PR [] = $prize _arr[$i] [' Prize '];} $res [' no '] = $PR; Echo json_ Encode ($res);   

PHP probabilistic algorithm (RPM)