php如何实现计算抽奖概率的算法实例分享

<?php
  //计算抽奖的概率
  function get_rand($proArr) {
    $result = &#39;&#39;;
    $proSum = array_sum($proArr);
    foreach ($proArr as $key => $proCur) {
      $randNum = mt_rand(1, $proSum);
      if ($randNum <= $proCur) {
        $result = $key;
        break;
      } else {
        $proSum -= $proCur;
      }
    }
    unset ($proArr);
    return $result;
  }
  $prize_arr = array(
    &#39;0&#39; => array(&#39;id&#39;=>1,&#39;prize&#39;=>&#39;家电&#39;,&#39;v&#39;=>2),
    &#39;1&#39; => array(&#39;id&#39;=>2,&#39;prize&#39;=>&#39;数码相机&#39;,&#39;v&#39;=>5),
    &#39;2&#39; => array(&#39;id&#39;=>3,&#39;prize&#39;=>&#39;iPad&#39;,&#39;v&#39;=>13),
    &#39;3&#39; => array(&#39;id&#39;=>4,&#39;prize&#39;=>&#39;LED显示器&#39;,&#39;v&#39;=>15),
    &#39;4&#39; => array(&#39;id&#39;=>5,&#39;prize&#39;=>&#39;U盘&#39;,&#39;v&#39;=>25),
    &#39;5&#39; => array(&#39;id&#39;=>6,&#39;prize&#39;=>&#39;键盘&#39;,&#39;v&#39;=>30),
    &#39;6&#39; => array(&#39;id&#39;=>7,&#39;prize&#39;=>&#39;鼠标垫&#39;,&#39;v&#39;=>10),
  );
  foreach ($prize_arr as $key => $val) {
    $arr[$val[&#39;id&#39;]] = $val[&#39;v&#39;];
  }
  $rid = get_rand($arr);
  $res[&#39;yes&#39;] = $prize_arr[$rid-1][&#39;prize&#39;];
  unset($prize_arr[$rid-1]);
  shuffle($prize_arr);
  $prize_arrcount = count($prize_arr);
  for($i=0;$i<$prize_arrcount;$i++){
    $pr[] = $prize_arr[$i][&#39;prize&#39;];
  }
  $res[&#39;no&#39;] = $pr;
  //抽奖结果
  $ro = $res[&#39;yes&#39;];
  print_r($ro);
?>

iPad