Php random lottery code

This article will share with you the code that uses php to calculate the random lottery probability based on the Prize weight. it is very useful. if you have similar requirements, you can refer to the following 1. initial data:

A higher weight indicates a higher probability of extraction.
[Prize 1, weight 5], [Prize 2, weight 6], [prize 3, weight 7], [prize 4, weight 2]

2. Procedure:

1) N = 5 + 6 + 7 + 2 = 20
2) Then, take the random number M from 1 to n.
3) define the weight range of each prize; 1: 1-5; 2: 6-11; 3: 12-18; and 4: 19-20.
4) If M is within the weight range of a prize, mark the prize to be extracted.

<? Php/*** Prize */class Prize {# ID public $ id = null; # weight public $ weight = null; # Prize name public $ name = null; # protected $ start = 0; # protected $ end = 0; public function _ construct ($ id, $ weight, $ name) {if (! $ Id) {throw new Exception ('prize ID is empty. ') ;}$ this-> id = $ id; $ this-> weight = $ weight? $ Weight: 0; $ this-> name = $ name? $ Name: 'Random prize '. $ id ;}# id public function getId () {return $ this-> id ;}# weight public function getWeight () {return $ this-> weight ;} # set the weight range public function setRange ($ start, $ end) {$ this-> start = $ start; $ this-> end = $ end ;} # determine whether a random number is in the public function inRange ($ num) {return ($ num >=$ this-> start) in the weight range) & ($ num <= $ this-> end) ;}/ *** prize pool */class PrizePoll implements IteratorAggregate, Count Able {# Prize set protected $ items = array (); # add public function addItem (Prize $ item) {$ this-> items [$ item-> getId ()] = $ item; return $ this ;}# delete prize public function removeItem ($ itemId) {if (isset ($ this-> items [$ itemId]) {unset ($ this-> items [$ itemId]);} return $ this;} # Update Prize public function updateItem (Prize $ item) {if (isset ($ this-> items [$ item-> getId ()]) {$ this-> items [$ item-> getId ()] = $ item;} Return $ this ;}# get all prizes public function getItems () {return $ this-> items ;}# all available prizes (if the weight is 0, it indicates that this prize will never be obtained.) public function getVisibleItems () {$ items = array (); foreach ($ this-> items as $ item) {if ($ item-> getWeight () {$ items [$ item-> getId ()] = $ item ;}} return $ items ;}# Countable :: count public function count () {return count ($ this-> items) ;}# IteratorAggregate: getIterator () public func Tion getIterator () {return new ArrayIterator ($ this-> items) ;}/ *** simple lucky draw class */class SimpleTurn {# prize pool protected $ poll = null; public function _ construct (PrizePoll $ poll) {if ($ poll) {$ this-> setPoll ($ poll) ;}# lottery public function run (PrizePoll $ poll) {$ poll = $ poll? $ Poll: $ this-> poll; if (! $ Poll) {throw new Exception ('award pool not initialized ');} if ($ poll-> count () <= 0) {throw new Exception ('empty prize pool ') ;}$ items = $ poll-> getVisibleItems (); if (count ($ items) <= 0) {throw new Exception ('empty prize pool ');} $ sum = 0; foreach ($ items as $ item) {$ start = $ sum + 1; $ sum + = $ item-> getWeight (); $ end = $ sum; # set the weight range of the prize $ item-> setRange ($ start, $ end );} # Random number $ rand = $ this-> getRandNum (1, $ sum); # foreach ($ ite MS as $ item) {if ($ item-> inRange ($ rand) {return $ item;} return null ;}# obtain the random number public function getRandNum ($ min, $ max) {return mt_rand ($ min? $ Min: 1, $ max) ;}# set public function setPoll (PrizePoll $ poll) {$ this-> poll = $ poll ;}} # Example try {$ prizePoll = new PrizePoll (); $ prizePoll-> addItem (new Prize (1, 5)-> addItem (new Prize (2, 6 )) -> addItem (new Prize (3, 7)-> addItem (new Prize (4, 2); $ turn = new SimpleTurn ($ prizePoll ); $ prize = $ turn-> run (); var_dump ($ prize);} catch (Exception $ e) {print_r ($ e );}