blocks|key|84716|text|递归确实简化了它：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|84717|public+static+void+permutation(String+str)+
{+
++++permutation("",+str);+
}

private+static+void+permutation(String+prefix,+String+str)+
{
++++int+n+=+str.length();
++++if+(n+==+0)+{
++++++++System.out.println(prefix);
++++}+else+{
++++++++for+(int+i+=+0;+i+<+n;+i%2B%2B)
++++++++++++permutation(prefix+%2B+str.charAt(i),+str.substring(0,+i)+%2B+str.substring(i%2B1,+n));
++++}
}|code-block|syntax|javascript|84718|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Recursion really simplifies it:

<pre><code>public static void permutation(String str) 
{ 
 permutation("", str); 
}

private static void permutation(String prefix, String str) 
{
 int n = str.length();
 if (n == 0) {
 System.out.println(prefix);
 } else {
 for (int i = 0; i &lt; n; i++)
 permutation(prefix + str.charAt(i), str.substring(0, i) + str.substring(i+1, n));
 }
}
</code></pre>

blocks|key|302183|text|#+include+<stdio.h>

/*+Function+to+swap+values+at+two+pointers+*/
void+swap+(char+*x,+char+*y)
{
+++++char+temp;
+++++temp+=+*x;
+++++*x+=+*y;
+++++*y+=+temp;
}

/*+Function+to+print+permutations+of+string
++++This+function+takes+three+parameters:
++++1.+String
++++2.+Starting+index+of+the+string
++++3.+Ending+index+of+the+string.+*/
void+permute(char+*a,+int+i,+int+n)
{
++++int+j;
++++if+(i+==+n)
++++++printf("%25s\n",+a);
++++else
++++{
++++++++++for+(j+=+i;+j+<=+n;+j%2B%2B)
+++++++++{
+++++++++++++swap((a%2Bi),+(a%2Bj));
+++++++++++++permute(a,+i%2B1,+n);
+++++++++++++swap((a%2Bi),+(a%2Bj));+//backtrack
+++++++++}
++++}
}

/*+Driver+program+to+test+above+functions+*/
int+main()
{
++++char+a[]+=+"ABC";
++++permute(a,+0,+2);
++++getchar();
++++return+0;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|302184|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code># include &lt;stdio.h&gt;

/* Function to swap values at two pointers */
void swap (char *x, char *y)
{
 char temp;
 temp = *x;
 *x = *y;
 *y = temp;
}

/* Function to print permutations of string
 This function takes three parameters:
 1. String
 2. Starting index of the string
 3. Ending index of the string. */
void permute(char *a, int i, int n)
{
 int j;
 if (i == n)
 printf("%s\n", a);
 else
 {
 for (j = i; j &lt;= n; j++)
 {
 swap((a+i), (a+j));
 permute(a, i+1, n);
 swap((a+i), (a+j)); //backtrack
 }
 }
}

/* Driver program to test above functions */
int main()
{
 char a[] = "ABC";
 permute(a, 0, 2);
 getchar();
 return 0;
}
</code></pre>

blocks|key|302189|text|伪代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|302190|String+permute(String+a[])
{
++if+(a[].length+==+1)
+++++return+a[];
++for+(i+=+0,+i+<+a[].length();+i%2B%2B)
++++append(a[i],+permute(a[].remove(i)));
}|code-block|syntax|javascript|302191|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Pseudo code:

<pre><code>String permute(String a[])
{
 if (a[].length == 1)
 return a[];
 for (i = 0, i &lt; a[].length(); i++)
 append(a[i], permute(a[].remove(i)));
}
</code></pre>

blocks|key|84738|text|I+create+more+specific+but+not+efficient+Program+for+permutation+for+general+string.
It's+work+nice+way.
//ubuntu+13.10+and+g%2B%2B+compiler+but+it's+works+on+any+platform+and+OS
//All+Permutation+of+general+string.

#include<iostream>
#include<stdio.h>
#include<string>
#include<string.h>
using+namespace+std;
int+len;
string+str;

void+permutation(int+cnum)
{
++++int+mid;
++++int+flag=1;
++++int+giga=0;
++++int+dead=0;
++++int+array[50];
++++for(int+i=0;i<len-1;i%2B%2B)
++++{
++++++++array[50]='\0';
++++++++dead=0;
++++++++for(int+j=cnum;j<len%2Bcnum;j%2B%2B)
++++++++{
++++++++++++mid=j%25len;
++++++++++++if(mid==cnum+&&+flag==1)
++++++++++++{
++++++++++++++++cout<<str[mid];
++++++++++++++++array[dead]=mid;
++++++++++++++++dead%2B%2B;
++++++++++++++++flag=0;
++++++++++++}
++++++++++++++++else
++++++++++++{
++++++++++++++++giga=(i%2Bj)%25len;
++++++++++++++++for(int+k=0;k<dead;k%2B%2B)+++++++++++++++++
++++++++++++++++{
++++++++++++++++++++if((array[k]==giga)+&&+flag==0)
++++++++++++++++++++{
++++++++++++++++++++giga=(giga%2B1)%25len;
++++++++++++++++++++}
++++++++++++++++}
++++++++++++++++cout<<str[giga];
++++++++++++++++array[dead]=giga;
++++++++++++++++dead%2B%2B;

++++++++++++}
++++++++}
++++++++cout<<endl;
++++++++flag=1;+
++++}
}
int+main()
{
++++cout<<"Enter+the+string+::+";
++++getline(cin,str);
++++len=str.length();
++++cout<<"String+length+=+"<<len<<endl;
++++cout<<"Total+permutation+=+"<<len*(len-1)<<endl;
++++for(int+j=0;j<len;j%2B%2B)
++++{
++++++++permutation(j);
++++}
return+0;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|84739|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>I create more specific but not efficient Program for permutation for general string.
It's work nice way.
//ubuntu 13.10 and g++ compiler but it's works on any platform and OS
//All Permutation of general string.

#include&lt;iostream&gt;
#include&lt;stdio.h&gt;
#include&lt;string&gt;
#include&lt;string.h&gt;
using namespace std;
int len;
string str;

void permutation(int cnum)
{
 int mid;
 int flag=1;
 int giga=0;
 int dead=0;
 int array[50];
 for(int i=0;i&lt;len-1;i++)
 {
 array[50]='\0';
 dead=0;
 for(int j=cnum;j&lt;len+cnum;j++)
 {
 mid=j%len;
 if(mid==cnum &amp;&amp; flag==1)
 {
 cout&lt;&lt;str[mid];
 array[dead]=mid;
 dead++;
 flag=0;
 }
 else
 {
 giga=(i+j)%len;
 for(int k=0;k&lt;dead;k++) 
 {
 if((array[k]==giga) &amp;&amp; flag==0)
 {
 giga=(giga+1)%len;
 }
 }
 cout&lt;&lt;str[giga];
 array[dead]=giga;
 dead++;

 }
 }
 cout&lt;&lt;endl;
 flag=1; 
 }
}
int main()
{
 cout&lt;&lt;"Enter the string :: ";
 getline(cin,str);
 len=str.length();
 cout&lt;&lt;"String length = "&lt;&lt;len&lt;&lt;endl;
 cout&lt;&lt;"Total permutation = "&lt;&lt;len*(len-1)&lt;&lt;endl;
 for(int j=0;j&lt;len;j++)
 {
 permutation(j);
 }
return 0;
}
</code></pre>

blocks|key|84741|text|def+perms(s):
++++if+len(s)+<+1:
++++++++return+[s]
++++ps+=+[]
++++for+i+in+range(0,+len(s)):
++++++++head,+tail+=+s[i],+s[0:i]+%2B+s[i+%2B+1:]
++++++++ps.extend([head+%2B+tailp+for+tailp+in+perms(tail)])
++++return+ps|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|84742|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>def perms(s):
 if len(s) &lt; 1:
 return [s]
 ps = []
 for i in range(0, len(s)):
 head, tail = s[i], s[0:i] + s[i + 1:]
 ps.extend([head + tailp for tailp in perms(tail)])
 return ps
</code></pre>

I am learning backtracking and recursion and I am stuck at an algorithm for printing all the permutations of a string. I solved it using the <a href="http://programminggeeks.com/bell-algorithm-for-permutation/" rel="nofollow noreferrer">bell algorithm</a> for permutation but I am not able to understand the recursion method. I searched the web and found this code:

<pre><code>void permute(char *a, int i, int n) 
{
 int j; 
 if (i == n)
 printf("%s\n", a);
 else
 {
 for (j = i; j &lt;= n; j++)
 {
 swap((a+i), (a+j));
 permute(a, i+1, n);
 swap((a+i), (a+j)); 
 }
 }
} 
</code></pre>

How is this algorithm basically working I am unable to understand? I even tried dry running!

How is the backtracking applied?

And is it more efficient than the Bell Algorithm for calculation of permutation?

Print all the permutations of a string in C

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在学习回溯和递归，并且我被一种打印字符串的所有排列的算法所困扰。我用置换的解决了这个问题，但是我不能理解递归方法。我在网上搜索了一下，发现了下面的代码：void permute(char *a, int i, int n) {   int j;    if (i == n)     printf("%s\n", a...

问打印C语言中字符串的所有排列
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