全排列算法的递归与非递归实现

全排列算法的递归与非递归实现

全排列算法是常见的算法，用于求一个序列的全排列，本文使用C语言分别用递归与非递归两种方法实现，可以接受元素各不相同的输入序列。

题目来自leetcode：

Given a collection of numbers, return all possible permutations.

For example,

[1,2,3] have the following permutations:

[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].

递归实现

对于序列Sn={s0,s1,…,sn},其全排列可以看做s0与后面的n-1个元素交换，然后后面的n-1个元素再次进行全排列。也就是说Sn的全排列可以写为{s0,Sn-1},{s1,Sn-1},…{sn,Sn-1}。以此类推。这显然是一个递归的过程。

<code class="language-c hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include<stdio.h></span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include<stdlib.h></span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> swap(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *a, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *b)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> temp;
temp = *a;
*a = *b;
*b = temp;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> permut(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **result, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numbers[], <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> n, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *rows, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> m)
{<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//完成下标为m到n的全排列</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (m == n)
{<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//已经处理到最后一个元素，递归返回</span>
(*rows)--;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i < n; i++)
result[(*rows)][i] = numbers[i];
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span>
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = m; i < n; i++)
{
swap(&numbers[m], &numbers[i]);<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//交换</span>
permut(result, numbers, n, rows, m + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>);<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//向后处理</span>
swap(&numbers[m], &numbers[i]);<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//再次交换</span>
}
}
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **permute(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numbers[], <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> n, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *numRows)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **result, i;
*numRows = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//计算全排列数</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = n; i><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>; i--)
(*numRows) *= i;
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//分配结果数组</span>
result = (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **)<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">malloc</span>((*numRows)*<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">sizeof</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i<(*numRows); i++)
*(result + i) = (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *)<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">malloc</span>(n*<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">sizeof</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> rows = *numRows;
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//从第一个元素开始排列</span>
permut(result, numbers, n, &rows, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>);

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> result;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> main()
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i, j;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numbers[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>] = {<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>};
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numRows = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, n = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **result = permute(numbers, n, &numRows);

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i<numRows; i++)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (j = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; j<n; j++)
{
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">printf</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%d "</span>, result[i][j]);
}
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">printf</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"\n"</span>);
}
system(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"pause"</span>);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li><li style="box-sizing: border-box; padding: 0px 5px;">52</li><li style="box-sizing: border-box; padding: 0px 5px;">53</li><li style="box-sizing: border-box; padding: 0px 5px;">54</li><li style="box-sizing: border-box; padding: 0px 5px;">55</li><li style="box-sizing: border-box; padding: 0px 5px;">56</li><li style="box-sizing: border-box; padding: 0px 5px;">57</li><li style="box-sizing: border-box; padding: 0px 5px;">58</li><li style="box-sizing: border-box; padding: 0px 5px;">59</li><li style="box-sizing: border-box; padding: 0px 5px;">60</li><li style="box-sizing: border-box; padding: 0px 5px;">61</li><li style="box-sizing: border-box; padding: 0px 5px;">62</li><li style="box-sizing: border-box; padding: 0px 5px;">63</li></ul>

非递归实现

非递归实现全排列的思想是：

1,将序列排序，生成最小序列Smin

2,然后找到比Smin大但比其他序列都小的序列Smin+1

3,反复执行2,直到序列最大

比如序列{2,1,3}，首先排序得到最小序列{1,2,3}，然后找到次小的序列{1,3,2}，然后是{2,1,3}……以此类推直到序列{3,2,1}结束。

其算法是在序列{s0,s1,…si,sj,…sk,…,sn-1}中

1,从后向前查找,找到第一个si<sj,如果i=0时依然没有找到，说明该序列已经最大，返回。

2,从后向前查找，找到第一个比si大的元素sk，交换si和sk。为了保证得到的是次小的序列，将序列si+1到sn-1逆向。

3,重复1、2两步直到退出

<code class="language-c hljs  has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include<stdio.h></span>
<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">#include<stdlib.h></span>

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> swap(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *a, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *b)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> temp;
temp = *a;
*a = *b;
*b = temp;
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> sort(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numbers[], <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> n)
{<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//冒泡排序</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i, j, k;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i < n; i++)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (j = i + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>; j < n; j++)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (numbers[i]>numbers[j])
swap(&numbers[i], &numbers[j]);
}
}
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> reverse(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numbers[], <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> j)
{<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//逆置</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> p, q;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (p = i, q = j; p < q; p++, q--)
swap(&numbers[p], &numbers[q]);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> store(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **result, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numbers[], <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> n, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> row)
{<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//将序列存入结果数组中</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i < n; i++)
result[row][i] = numbers[i];
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **permute(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numbers[], <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> n, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *numRows)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **result, i,j,row;
*numRows = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = n; i><span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>; i--)
(*numRows) *= i;
result = (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **)<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">malloc</span>((*numRows)*<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">sizeof</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i<(*numRows); i++)
*(result + i) = (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> *)<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">malloc</span>(n*<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">sizeof</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span>));
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//首先对序列进行排序，找到最小序列</span>
sort(numbers,n);
row = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">while</span> (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">true</span>)
{
store(result, numbers, n, row++);
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//找到第一个比后一个元素小的元素numbers[i]</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (n < <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//当序列只有一个元素时直接退出</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> result;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = n - <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>; i >= <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i--)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (numbers[i] < numbers[i + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>])
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">else</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (i == <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>)
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> result;
}
<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//找到从后面开始比numbers[i]大的第一个元素</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (j = n - <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>; j > i; j--)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (numbers[j] > numbers[i])
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">break</span>;
}
swap(&numbers[i], &numbers[j]);
reverse(numbers, i + <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>, n-<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>);

}
}

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> main()
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> i, j;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numbers[<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>] = {<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">2</span>,<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>};
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> numRows = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>, n = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3</span>;

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> **result = permute(numbers, n, &numRows);

<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (i = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; i<numRows; i++)
{
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span> (j = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0</span>; j<n; j++)
{
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">printf</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%d "</span>, result[i][j]);
}
<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">printf</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"\n"</span>);
}
system(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"pause"</span>);
}</code>