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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，
* $PRoArr是一個(gè)預(yù)先設(shè)置的數(shù)組，
* 假設(shè)數(shù)組為：array(100,200,300，400)，
* 開始是從1,1000 這個(gè)概率范圍內(nèi)篩選第一個(gè)數(shù)是否在他的出現(xiàn)概率范圍之內(nèi)，
* 如果不在，則將概率空間，也就是k的值減去剛剛的那個(gè)數(shù)字的概率空間，
* 在本例當(dāng)中就是減去100，也就是說第二個(gè)數(shù)是在1，900這個(gè)范圍內(nèi)篩選的。
* 這樣 篩選到最終，總會(huì)有一個(gè)數(shù)滿足要求。
* 就相當(dāng)于去一個(gè)箱子里摸東西，
* 第一個(gè)不是，第二個(gè)不是，第三個(gè)還不是，那最后一個(gè)一定是。
* 這個(gè)算法簡(jiǎn)單，而且效率非常 高，
* 關(guān)鍵是這個(gè)算法已在我們以前的項(xiàng)目中有應(yīng)用，尤其是大數(shù)據(jù)量的項(xiàng)目中效率非常棒。
</span><span style="color: #008000;">*/</span>
<span style="color: #0000ff;">function</span> get_rand(<span style="color: #800080;">$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(jiǎng)項(xiàng)數(shù)組
* 是一個(gè)二維數(shù)組，記錄了所有本次抽獎(jiǎng)的獎(jiǎng)項(xiàng)信息，
* 其中id表示中獎(jiǎng)等級(jí)，prize表示獎(jiǎng)品，v表示中獎(jiǎng)概率。
* 注意其中的v必須為整數(shù)，你可以將對(duì)應(yīng)的 獎(jiǎng)項(xiàng)的v設(shè)置成0，即意味著該獎(jiǎng)項(xiàng)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(zhǔn)確性。
* 本例中v的總和為100，那么平板電腦對(duì)應(yīng)的 中獎(jiǎng)概率就是1%，
* 如果v的總和是10000，那中獎(jiǎng)概率就是萬分之一了。
*
</span><span style="color: #008000;">*/</span>
<span style="color: #800080;">$prize_arr</span> = <span style="color: #0000ff;">array</span><span style="color: #000000;">(
</span>'0' => <span style="color: #0000ff;">array</span>('id'=>1,'prize'=>'平板電腦','v'=>1),
'1' => <span style="color: #0000ff;">array</span>('id'=>2,'prize'=>'數(shù)碼相機(jī)','v'=>5),
'2' => <span style="color: #0000ff;">array</span>('id'=>3,'prize'=>'音箱設(shè)備','v'=>10),
'3' => <span style="color: #0000ff;">array</span>('id'=>4,'prize'=>'4G優(yōu)盤','v'=>12),
'4' => <span style="color: #0000ff;">array</span>('id'=>5,'prize'=>'10Q幣','v'=>22),
'5' => <span style="color: #0000ff;">array</span>('id'=>6,'prize'=>'下次沒準(zhǔn)就能中哦','v'=>50),<span style="color: #000000;">
);
</span><span style="color: #008000;">/*</span><span style="color: #008000;">
* 每次前端頁面的請(qǐng)求，PHP循環(huán)獎(jiǎng)項(xiàng)設(shè)置數(shù)組，
* 通過概率計(jì)算函數(shù)get_rand獲取抽中的獎(jiǎng)項(xiàng)id。
* 將中獎(jiǎng)獎(jiǎng)品保存在數(shù)組$res['yes']中，
* 而剩下的未中獎(jiǎng)的信息保存在$res['no']中，
* 最后輸出json個(gè)數(shù)數(shù)據(jù)給前端頁面。
</span><span style="color: #008000;">*/</span>
<span style="color: #0000ff;">foreach</span> (<span style="color: #800080;">$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;">$arr</span>); <span style="color: #008000;">//</span><span style="color: #008000;">根據(jù)概率獲取獎(jiǎng)項(xiàng)id </span>
<span style="color: #800080;">$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(jiǎng)項(xiàng) </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(jiǎng)項(xiàng)從數(shù)組中剔除，剩下未中獎(jiǎng)項(xiàng) </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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