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浅谈php随机不重复数的两种算法

php中文网
发布： 2016-06-06 19:50:48
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1885人浏览过

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@gmail.com>
</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> ?>
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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><<span>$no</span>;<span>$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> < <span>$num</span><span>) {
</span><span>26</span>             <span>$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> < <span>count</span>(<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> ?>
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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.
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立即学习“PHP免费学习笔记（深入）”；

结论：对于从大量数据中取少量数据，显然第二种比较快。

 

立即学习“PHP免费学习笔记（深入）”；

2.在来看看从大数中取大数：

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<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><<span>$no</span>;<span>$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> < <span>$num</span><span>) {
</span><span>26</span>             <span>$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> < <span>count</span>(<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> ?>
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输出结果为：

<span>1</span> <span>前面省略&hellip;&hellip;&hellip;&hellip;&hellip;&hellip;
</span><span>2</span> div 1 Duration: 0.6050 seconds.
<span>3</span> div 2 Duration: 17.4260 seconds.
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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。

 

立即学习“PHP免费学习笔记（深入）”；

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。

 

立即学习“PHP免费学习笔记（深入）”；

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