PermuteLexicographically.txt

How to permute a string and print in lexicographically order?
Things to remember:
   1  Sort the string;          // necessary to get LEXICOGRAPHICALLY
   2  keep sorted string in an arry and use it for getting characters in sorted form
   3  Dont send copy of use[] arry .... Send its pointer, because we need to know waht has been used ... try pen & paper to know how 
      it works
      

CODE:// similar to anagram ques of karumanchi
#include <iostream>
#include <algorithm>
#include <string.h>
#include<string>
using namespace std;

void permute(char *p, int depth , char *st , bool *use)
{
	static int count=0;
	int l=strlen(st);
	if(depth== l)
	  {
	  	cout<< count++<<"\t";printf("%s\n",p);
	  	return;
	  }
    
	  int i=0;
	 for(i=0;i<l;i++)
	 {
	 	if(!use[i])
	 	{
	 		use[i]=true;                //it is very neccessary TO USE SAME use[] ARRAY
	 		p[depth]=st[i];
	 		permute(p,depth+1,st,use);
	 		use[i]=false;
	 	}
	 }
	
}


int main() {
char s[]="ABGS";       // for "ABGS" there are 4*3*2*1 = 4! = 24 orders.
int l=strlen(s),i=0;
bool use[l+2];
for(i=0;i<l+2;i++)
use[i]=false;
char p[l+2];
permute(p,0,s,use);
return 0;
}


 OUTPUT:
 0	ABGS
1	ABSG
2	AGBS
3	AGSB
4	ASBG
5	ASGB
6	BAGS
7	BASG
8	BGAS
9	BGSA
10	BSAG
11	BSGA
12	GABS
13	GASB
14	GBAS
15	GBSA
16	GSAB
17	GSBA
18	SABG
19	SAGB
20	SBAG
21	SBGA
22	SGAB
23	SGBA