浅谈php随机不重复数的两种算法-php手册-php.cn

Home

php教程

php手册

浅谈php随机不重复数的两种算法

WBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWBOYWB

Jun 06, 2016 pm 07:50 PM

phppluralintroducealgorithmrandom

先引入别人的一个秒表计时类（counttime.class.php）： 1.先看第一个例子（大数中取少数）： 1 ? 2 /* 3 @描述: Stopwatch这个类用户获取脚本执行时间 4 @作者: Klesti Hoxha klesti@gmail.com 5 */ 6 7 class Stopwatch { 8 private $start ; 9 private $en

先引入别人的一个秒表计时类（counttime.class.php）：

1.先看第一个例子（大数中取少数）：

<span> 1</span> 
<span> 2</span> <span>/*</span>
<span> 3</span> <span>@描述: Stopwatch这个类用户获取脚本执行时间
</span><span> 4</span> <span>@作者: Klesti Hoxha <klesti>
</klesti></span><span> 5</span> <span>*/</span>
<span> 6</span> 
<span> 7</span> <span>class</span><span> Stopwatch {
</span><span> 8</span> <span>private</span> <span>$start</span><span>;
</span><span> 9</span> <span>private</span> <span>$end</span><span>;
</span><span>10</span> <span>private</span> <span>$markup_start</span> = <span>array</span><span>();
</span><span>11</span> <span>private</span> <span>$markup_end</span> = <span>array</span><span>();
</span><span>12</span> 
<span>13</span> <span>function</span> __construct(<span>$markup</span>=<span>false</span><span>) {
</span><span>14</span> <span>$this</span>->start(<span>$markup</span><span>);
</span><span>15</span> <span>}
</span><span>16</span> 
<span>17</span> <span>public</span> <span>function</span> start(<span>$markup</span>=<span>false</span><span>) {
</span><span>18</span> <span>if</span> (!<span>$markup</span><span>) {
</span><span>19</span> <span>$this</span>->start = <span>$this</span>-><span>getmicrotime();
</span><span>20</span> } <span>else</span><span> {
</span><span>21</span> <span>$this</span>->markup_start[<span>$markup</span>] = <span>$this</span>-><span>getmicrotime();
</span><span>22</span> <span>}
</span><span>23</span> <span>}
</span><span>24</span> 
<span>25</span> <span>public</span> <span>function</span> stop(<span>$markup</span>=<span>false</span><span>) {
</span><span>26</span> <span>if</span> (!<span>$markup</span><span>) {
</span><span>27</span> <span>$this</span>-><span>end</span> = <span>$this</span>-><span>getmicrotime();
</span><span>28</span> } <span>else</span><span> {
</span><span>29</span> <span>$this</span>->markup_end[<span>$markup</span>] = <span>$this</span>-><span>getmicrotime();
</span><span>30</span> <span>}
</span><span>31</span> <span>return</span> <span>$this</span>->getDuration(<span>$markup</span><span>);
</span><span>32</span> <span>}
</span><span>33</span> 
<span>34</span> <span>public</span> <span>function</span> getDuration(<span>$markup</span>=<span>false</span><span>) {
</span><span>35</span>     <span>if</span> (!<span>$markup</span><span>)
</span><span>36</span> <span>     {
</span><span>37</span>         <span>return</span> <span>number_format</span>(<span>$this</span>-><span>end</span>-<span>$this</span>->start,4<span>);
</span><span>38</span>     } <span>else</span><span> {
</span><span>39</span>         <span>return</span> <span>number_format</span>(<span>$this</span>->markup_end[<span>$markup</span>]-<span>$this</span>->markup_start[<span>$markup</span>],4<span>);
</span><span>40</span> <span>    }
</span><span>41</span> <span>}
</span><span>42</span> 
<span>43</span> <span>public</span> <span>function</span> <span>reset</span>(<span>$markup</span><span>) {
</span><span>44</span> <span>if</span> (!<span>$markup</span><span>) {
</span><span>45</span> <span>$this</span>->start = 0<span>;
</span><span>46</span> <span>$this</span>-><span>end</span> = 0<span>;
</span><span>47</span> <span>$this</span>->markup_start = <span>array</span><span>();
</span><span>48</span> <span>$this</span>->markup_end = <span>array</span><span>();
</span><span>49</span> } <span>else</span><span> {
</span><span>50</span> <span>$this</span>->markup_start[<span>$markup</span>] = 0<span>;
</span><span>51</span> <span>$this</span>->markup_end[<span>$markup</span>] = 0<span>;
</span><span>52</span> <span>}
</span><span>53</span> <span>}
</span><span>54</span> 
<span>55</span> <span>private</span> <span>function</span><span> getmicrotime(){
</span><span>56</span> <span>list</span>(<span>$usec</span>, <span>$sec</span>) = <span>explode</span>(" ",<span>microtime</span><span>());
</span><span>57</span> <span>return</span> ((<span>float</span>)<span>$usec</span> + (<span>float</span>)<span>$sec</span><span>);
</span><span>58</span> <span>}
</span><span>59</span> 
<span>60</span> <span>}
</span><span>61</span> ?>

测试的两种方法如下：

<span> 1</span> <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<span> 2</span> <span>php
</span><span> 3</span> <span>require</span> "counttime.class.php";<span>//</span><span>把类文件引用进来，根据你的实际情况来确定路径，这里是在同级目录</span>
<span> 4</span> <span>$s</span> = <span>new</span><span> Stopwatch();
</span><span> 5</span> 
<span> 6</span> <span>$s</span>->start("div1"<span>);
</span><span> 7</span> <span>//</span><span>range 是将1到100 列成一个数组</span>
<span> 8</span> <span>$numbers</span> = <span>range</span> (1,1000000<span>);
</span><span> 9</span> <span>//</span><span>shuffle 将数组顺序随即打乱</span>
<span>10</span> <span>shuffle</span> (<span>$numbers</span><span>);
</span><span>11</span> <span>//</span><span>array_slice 取该数组中的某一段</span>
<span>12</span> <span>$no</span>=30<span>;
</span><span>13</span> <span>$result</span> = <span>array_slice</span>(<span>$numbers</span>,0,<span>$no</span><span>);
</span><span>14</span> <span>for</span> (<span>$i</span>=0;<span>$i</span>$no;<span>$i</span>++<span>){
</span><span>15</span> <span>echo</span> <span>$result</span>[<span>$i</span>]."<br>"<span>;
</span><span>16</span> <span>}
</span><span>17</span> <span>echo</span> "第一个测验方法结束<br><br>"<span>;
</span><span>18</span> <span>$s</span>->stop("div1"<span>);
</span><span>19</span> 
<span>20</span> <span>$s</span>->start("div2"<span>);
</span><span>21</span> <span>function</span> unique_rand(<span>$min</span>, <span>$max</span>, <span>$num</span><span>)
</span><span>22</span> <span>{
</span><span>23</span>         <span>$count</span> = 0<span>;
</span><span>24</span>         <span>$return</span> = <span>array</span><span>();
</span><span>25</span>         <span>while</span> (<span>$count</span> $num<span>) {
</span><span>26</span>             <span>$return</span>[] = <span>mt_rand</span>(<span>$min</span>, <span>$max</span><span>);
</span><span>27</span>             <span>$return</span> = <span>array_flip</span>(<span>array_flip</span>(<span>$return</span><span>));
</span><span>28</span>             <span>$count</span> = <span>count</span>(<span>$return</span><span>);
</span><span>29</span> <span>        }
</span><span>30</span>         <span>shuffle</span>(<span>$return</span><span>);
</span><span>31</span>         <span>return</span> <span>$return</span><span>;
</span><span>32</span> <span>}
</span><span>33</span> 
<span>34</span>     <span>$arr</span> = unique_rand(1, 100000000000, 30<span>);
</span><span>35</span>     <span>$result</span> = ''<span>;
</span><span>36</span>     <span>for</span>(<span>$i</span>=0; <span>$i</span> count(<span>$arr</span>);<span>$i</span>++<span>)
</span><span>37</span> <span>    {
</span><span>38</span>         <span>$result</span> = <span>$arr</span>[<span>$i</span><span>];
</span><span>39</span>         <span>echo</span> <span>$result</span>."<br>"<span>;
</span><span>40</span> <span>    }
</span><span>41</span>     <span>$s</span>->stop("div2"<span>);
</span><span>42</span> 
<span>43</span> 
<span>44</span> <span>//</span><span>输出时间</span>
<span>45</span> <span>echo</span> "div 1 Duration: " . <span>$s</span>->getDuration("div1") . " seconds.<br>"<span>;
</span><span>46</span> <span>echo</span> "div 2 Duration: " . <span>$s</span>->getDuration("div2") . " seconds.<br>"<span>;
</span><span>47</span> ?>

结果为：

<span> 1</span> 413537
<span> 2</span> 198587
<span> 3</span> 60611
<span> 4</span> 599544
<span> 5</span> 946241
<span> 6</span> 462853
<span> 7</span> 570943
<span> 8</span> 980260
<span> 9</span> 717416
<span>10</span> 969324
<span>11</span> 292403
<span>12</span> 614443
<span>13</span> 769469
<span>14</span> 151951
<span>15</span> 167883
<span>16</span> 308727
<span>17</span> 342706
<span>18</span> 955659
<span>19</span> 112311
<span>20</span> 329008
<span>21</span> 182668
<span>22</span> 330600
<span>23</span> 921966
<span>24</span> 993143
<span>25</span> 369227
<span>26</span> 747066
<span>27</span> 793185
<span>28</span> 347872
<span>29</span> 439016
<span>30</span> 428600
<span>31</span> <span>第一个测验方法结束
</span><span>32</span> 
<span>33</span> 649589727
<span>34</span> 450823813
<span>35</span> 324717181
<span>36</span> 44553762
<span>37</span> 375669657
<span>38</span> 37128612
<span>39</span> 25135327
<span>40</span> 468454185
<span>41</span> 73395357
<span>42</span> 753960006
<span>43</span> 214455797
<span>44</span> 5367614
<span>45</span> 1153263961
<span>46</span> 17803441
<span>47</span> 669057198
<span>48</span> 55366324
<span>49</span> 1117343950
<span>50</span> 203530485
<span>51</span> 1160930064
<span>52</span> 326487914
<span>53</span> 565471236
<span>54</span> 7068443
<span>55</span> 846955001
<span>56</span> 832037489
<span>57</span> 1067813034
<span>58</span> 219239595
<span>59</span> 1069795964
<span>60</span> 1049898846
<span>61</span> 926301266
<span>62</span> 197341539
<span>63</span> div 1 Duration: 0.5800 seconds.
<span>64</span> div 2 Duration: 0.0000 seconds.

结论：对于从大量数据中取少量数据，显然第二种比较快。

2.在来看看从大数中取大数：

<span> 1</span> <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<span> 2</span> <span>php
</span><span> 3</span> <span>require</span> "counttime.class.php";<span>//</span><span>把类文件引用进来，根据你的实际情况来确定路径，这里是在同级目录</span>
<span> 4</span> <span>$s</span> = <span>new</span><span> Stopwatch();
</span><span> 5</span> 
<span> 6</span> <span>$s</span>->start("div1"<span>);
</span><span> 7</span> <span>//</span><span>range 是将1到100 列成一个数组</span>
<span> 8</span> <span>$numbers</span> = <span>range</span> (1,1000000<span>);
</span><span> 9</span> <span>//</span><span>shuffle 将数组顺序随即打乱</span>
<span>10</span> <span>shuffle</span> (<span>$numbers</span><span>);
</span><span>11</span> <span>//</span><span>array_slice 取该数组中的某一段</span>
<span>12</span> <span>$no</span>=10000<span>;
</span><span>13</span> <span>$result</span> = <span>array_slice</span>(<span>$numbers</span>,0,<span>$no</span><span>);
</span><span>14</span> <span>for</span> (<span>$i</span>=0;<span>$i</span>$no;<span>$i</span>++<span>){
</span><span>15</span> <span>echo</span> <span>$result</span>[<span>$i</span>]."<br>"<span>;
</span><span>16</span> <span>}
</span><span>17</span> <span>echo</span> "第一个测验方法结束<br><br>"<span>;
</span><span>18</span> <span>$s</span>->stop("div1"<span>);
</span><span>19</span> 
<span>20</span> <span>$s</span>->start("div2"<span>);
</span><span>21</span> <span>function</span> unique_rand(<span>$min</span>, <span>$max</span>, <span>$num</span><span>)
</span><span>22</span> <span>{
</span><span>23</span>         <span>$count</span> = 0<span>;
</span><span>24</span>         <span>$return</span> = <span>array</span><span>();
</span><span>25</span>         <span>while</span> (<span>$count</span> $num<span>) {
</span><span>26</span>             <span>$return</span>[] = <span>mt_rand</span>(<span>$min</span>, <span>$max</span><span>);
</span><span>27</span>             <span>$return</span> = <span>array_flip</span>(<span>array_flip</span>(<span>$return</span><span>));
</span><span>28</span>             <span>$count</span> = <span>count</span>(<span>$return</span><span>);
</span><span>29</span> <span>        }
</span><span>30</span>         <span>shuffle</span>(<span>$return</span><span>);
</span><span>31</span>         <span>return</span> <span>$return</span><span>;
</span><span>32</span> <span>}
</span><span>33</span> 
<span>34</span>     <span>$arr</span> = unique_rand(1, 1000000, 10000<span>);
</span><span>35</span>     <span>$result</span> = ''<span>;
</span><span>36</span>     <span>for</span>(<span>$i</span>=0; <span>$i</span> count(<span>$arr</span>);<span>$i</span>++<span>)
</span><span>37</span> <span>    {
</span><span>38</span>         <span>$result</span> = <span>$arr</span>[<span>$i</span><span>];
</span><span>39</span>         <span>echo</span> <span>$result</span>."<br>"<span>;
</span><span>40</span> <span>    }
</span><span>41</span>     <span>$s</span>->stop("div2"<span>);
</span><span>42</span> 
<span>43</span> 
<span>44</span> <span>//</span><span>输出时间</span>
<span>45</span> <span>echo</span> "div 1 Duration: " . <span>$s</span>->getDuration("div1") . " seconds.<br>"<span>;
</span><span>46</span> <span>echo</span> "div 2 Duration: " . <span>$s</span>->getDuration("div2") . " seconds.<br>"<span>;
</span><span>47</span> ?>

输出结果为：

<span>1</span> <span>前面省略………………
</span><span>2</span> div 1 Duration: 0.6050 seconds.
<span>3</span> div 2 Duration: 17.4260 seconds.

结论：对于第一种方法输出一个数据的时间，跟大数的数字时间差不多。但是第二个时间显然耗费得要离谱。达到了17.5秒。

总结：

1.翻翻法对于选少量数据好用，大量数据就会比较吃力。

Statement

The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress images for free

Clothoff.io

AI clothes remover

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Article

Roblox: Grow A Garden - Complete Mutation Guide

3 weeks agoByDDD

Roblox: Bubble Gum Simulator Infinity - How To Get And Use Royal Keys

3 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

How to fix KB5055612 fails to install in Windows 10?

3 weeks agoByDDD

Nordhold: Fusion System, Explained

3 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Mandragora: Whispers Of The Witch Tree - How To Unlock The Grappling Hook

3 weeks agoBy尊渡假赌尊渡假赌尊渡假赌

Hot Tools

SublimeText3 Mac version

God-level code editing software (SublimeText3)

Dreamweaver CS6

Visual web development tools

WebStorm Mac version

Useful JavaScript development tools

PhpStorm Mac version

The latest (2018.2.1) professional PHP integrated development tool

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

Hot Topics

1666

1425

1328

1273

1253