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Winning probability algorithm (php can be used for scratch cards, big wheel and other lottery algorithms)
Winning probability algorithm (php can be used for scratch cards, big wheel and other lottery algorithms)
Jul 06, 2016 pm 01:30 PM
PHP winning probability algorithm, which can be used for scratch cards, big wheel and other lottery algorithms. The usage is very simple, there are detailed comments in the code, you can understand it at a glance? php /* * Classic probability algorithm, * $PRoArr is a preset array, * Assume the array is: array(100,200,300, 400), * The beginning is Screen the first number from the probability range of 1,1000 to see if it is
PHP winning probability algorithm, which can be used for scratch cards, big wheel and other lottery algorithms. Usage is very simple, the code has detailed comments and instructions, and you can understand it at a glance
<?<span style="color: #000000;">php
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
* 經(jīng)典的概率算法，
* $PRoArr是一個預(yù)先設(shè)置的數(shù)組，
* 假設(shè)數(shù)組為：array(100,200,300，400)，
* 開始是從1,1000 這個概率范圍內(nèi)篩選第一個數(shù)是否在他的出現(xiàn)概率范圍之內(nèi)，
* 如果不在，則將概率空間，也就是k的值減去剛剛的那個數(shù)字的概率空間，
* 在本例當中就是減去100，也就是說第二個數(shù)是在1，900這個范圍內(nèi)篩選的。
* 這樣 篩選到最終，總會有一個數(shù)滿足要求。
* 就相當于去一個箱子里摸東西，
* 第一個不是，第二個不是，第三個還不是，那最后一個一定是。
* 這個算法簡單，而且效率非常 高，
* 關(guān)鍵是這個算法已在我們以前的項目中有應(yīng)用，尤其是大數(shù)據(jù)量的項目中效率非常棒。
</span><span style="color: #008000;">*/</span>
<span style="color: #0000ff;">function</span> get_rand(<span style="color: #800080;">$proArr</span><span style="color: #000000;">) {
</span><span style="color: #800080;">$result</span> = ''<span style="color: #000000;">;
</span><span style="color: #008000;">//</span><span style="color: #008000;">概率數(shù)組的總概率精度 </span>
<span style="color: #800080;">$proSum</span> = <span style="color: #008080;">array_sum</span>(<span style="color: #800080;">$proArr</span><span style="color: #000000;">);
</span><span style="color: #008000;">//</span><span style="color: #008000;">概率數(shù)組循環(huán) </span>
<span style="color: #0000ff;">foreach</span> (<span style="color: #800080;">$proArr</span> <span style="color: #0000ff;">as</span> <span style="color: #800080;">$key</span> => <span style="color: #800080;">$proCur</span><span style="color: #000000;">) {
</span><span style="color: #800080;">$randNum</span> = <span style="color: #008080;">mt_rand</span>(1, <span style="color: #800080;">$proSum</span><span style="color: #000000;">);
</span><span style="color: #0000ff;">if</span> (<span style="color: #800080;">$randNum</span> <= <span style="color: #800080;">$proCur</span><span style="color: #000000;">) {
</span><span style="color: #800080;">$result</span> = <span style="color: #800080;">$key</span><span style="color: #000000;">;
</span><span style="color: #0000ff;">break</span><span style="color: #000000;">;
} </span><span style="color: #0000ff;">else</span><span style="color: #000000;"> {
</span><span style="color: #800080;">$proSum</span> -= <span style="color: #800080;">$proCur</span><span style="color: #000000;">;
}
}
</span><span style="color: #0000ff;">unset</span> (<span style="color: #800080;">$proArr</span><span style="color: #000000;">);
</span><span style="color: #0000ff;">return</span> <span style="color: #800080;">$result</span><span style="color: #000000;">;
}
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
* 獎項數(shù)組
* 是一個二維數(shù)組，記錄了所有本次抽獎的獎項信息，
* 其中id表示中獎等級，prize表示獎品，v表示中獎概率。
* 注意其中的v必須為整數(shù)，你可以將對應(yīng)的 獎項的v設(shè)置成0，即意味著該獎項抽中的幾率是0，
* 數(shù)組中v的總和（基數(shù)），基數(shù)越大越能體現(xiàn)概率的準確性。
* 本例中v的總和為100，那么平板電腦對應(yīng)的 中獎概率就是1%，
* 如果v的總和是10000，那中獎概率就是萬分之一了。
*
</span><span style="color: #008000;">*/</span>
<span style="color: #800080;">$prize_arr</span> = <span style="color: #0000ff;">array</span><span style="color: #000000;">(
</span>'0' => <span style="color: #0000ff;">array</span>('id'=>1,'prize'=>'平板電腦','v'=>1),
'1' => <span style="color: #0000ff;">array</span>('id'=>2,'prize'=>'數(shù)碼相機','v'=>5),
'2' => <span style="color: #0000ff;">array</span>('id'=>3,'prize'=>'音箱設(shè)備','v'=>10),
'3' => <span style="color: #0000ff;">array</span>('id'=>4,'prize'=>'4G優(yōu)盤','v'=>12),
'4' => <span style="color: #0000ff;">array</span>('id'=>5,'prize'=>'10Q幣','v'=>22),
'5' => <span style="color: #0000ff;">array</span>('id'=>6,'prize'=>'下次沒準就能中哦','v'=>50),<span style="color: #000000;">
);
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
* 每次前端頁面的請求，PHP循環(huán)獎項設(shè)置數(shù)組，
* 通過概率計算函數(shù)get_rand獲取抽中的獎項id。
* 將中獎獎品保存在數(shù)組$res['yes']中，
* 而剩下的未中獎的信息保存在$res['no']中，
* 最后輸出json個數(shù)數(shù)據(jù)給前端頁面。
</span><span style="color: #008000;">*/</span>
<span style="color: #0000ff;">foreach</span> (<span style="color: #800080;">$prize_arr</span> <span style="color: #0000ff;">as</span> <span style="color: #800080;">$key</span> => <span style="color: #800080;">$val</span><span style="color: #000000;">) {
</span><span style="color: #800080;">$arr</span>[<span style="color: #800080;">$val</span>['id']] = <span style="color: #800080;">$val</span>['v'<span style="color: #000000;">];
}
</span><span style="color: #800080;">$rid</span> = get_rand(<span style="color: #800080;">$arr</span>); <span style="color: #008000;">//</span><span style="color: #008000;">根據(jù)概率獲取獎項id </span>
<span style="color: #800080;">$res</span>['yes'] = <span style="color: #800080;">$prize_arr</span>[<span style="color: #800080;">$rid</span>-1]['prize']; <span style="color: #008000;">//</span><span style="color: #008000;">中獎項 </span>
<span style="color: #0000ff;">unset</span>(<span style="color: #800080;">$prize_arr</span>[<span style="color: #800080;">$rid</span>-1]); <span style="color: #008000;">//</span><span style="color: #008000;">將中獎項從數(shù)組中剔除，剩下未中獎項 </span>
<span style="color: #008080;">shuffle</span>(<span style="color: #800080;">$prize_arr</span>); <span style="color: #008000;">//</span><span style="color: #008000;">打亂數(shù)組順序 </span>
<span style="color: #0000ff;">for</span>(<span style="color: #800080;">$i</span>=0;<span style="color: #800080;">$i</span><<span style="color: #008080;">count</span>(<span style="color: #800080;">$prize_arr</span>);<span style="color: #800080;">$i</span>++<span style="color: #000000;">){
</span><span style="color: #800080;">$pr</span>[] = <span style="color: #800080;">$prize_arr</span>[<span style="color: #800080;">$i</span>]['prize'<span style="color: #000000;">];
}
</span><span style="color: #800080;">$res</span>['no'] = <span style="color: #800080;">$pr</span><span style="color: #000000;">;
</span><span style="color: #008080;">print_r</span>(<span style="color: #800080;">$res</span>);
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