浅谈php随机不重复数的两种算法
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。

Alat AI Hot

Undresser.AI Undress
Apl berkuasa AI untuk mencipta foto bogel yang realistik

AI Clothes Remover
Alat AI dalam talian untuk mengeluarkan pakaian daripada foto.

Undress AI Tool
Gambar buka pakaian secara percuma

Clothoff.io
Penyingkiran pakaian AI

AI Hentai Generator
Menjana ai hentai secara percuma.

Artikel Panas

Alat panas

Notepad++7.3.1
Editor kod yang mudah digunakan dan percuma

SublimeText3 versi Cina
Versi Cina, sangat mudah digunakan

Hantar Studio 13.0.1
Persekitaran pembangunan bersepadu PHP yang berkuasa

Dreamweaver CS6
Alat pembangunan web visual

SublimeText3 versi Mac
Perisian penyuntingan kod peringkat Tuhan (SublimeText3)

Topik panas

Dalam bab ini, kita akan memahami Pembolehubah Persekitaran, Konfigurasi Umum, Konfigurasi Pangkalan Data dan Konfigurasi E-mel dalam CakePHP.

PHP 8.4 membawa beberapa ciri baharu, peningkatan keselamatan dan peningkatan prestasi dengan jumlah penamatan dan penyingkiran ciri yang sihat. Panduan ini menerangkan cara memasang PHP 8.4 atau naik taraf kepada PHP 8.4 pada Ubuntu, Debian, atau terbitan mereka

Untuk bekerja dengan tarikh dan masa dalam cakephp4, kami akan menggunakan kelas FrozenTime yang tersedia.

Untuk mengusahakan muat naik fail, kami akan menggunakan pembantu borang. Di sini, adalah contoh untuk muat naik fail.

Dalam bab ini, kita akan mempelajari topik berikut yang berkaitan dengan penghalaan ?

CakePHP ialah rangka kerja sumber terbuka untuk PHP. Ia bertujuan untuk menjadikan pembangunan, penggunaan dan penyelenggaraan aplikasi lebih mudah. CakePHP adalah berdasarkan seni bina seperti MVC yang berkuasa dan mudah difahami. Model, Pandangan dan Pengawal gu

Kod Visual Studio, juga dikenali sebagai Kod VS, ialah editor kod sumber percuma — atau persekitaran pembangunan bersepadu (IDE) — tersedia untuk semua sistem pengendalian utama. Dengan koleksi sambungan yang besar untuk banyak bahasa pengaturcaraan, Kod VS boleh menjadi c

Pengesah boleh dibuat dengan menambah dua baris berikut dalam pengawal.
