permut.bak

calculates the permutation

 // 
 // PERMUT.CPP 
 //
 // Program that can print the different permutations of an array of elements
 // passed (of any size). For example 123456 or abcdef etc.
 // To permute ver large numbers you must change the value of MAX_LEN.
 //
 // Date	: 7 april 2002
 // Author   	: Vivek Mohan
 // Homepage 	: http://www.geocities.com/cppresources/
 // Email	: [e-mail] || [e-mail]
 //
 // 
 // Sample Outputs for 123 , 12345 and abcd included in the package
 //
 //

 # include <iostream.h>
 # include <string.h>
 # include <conio.h>

 // Few Prototypes 

 void rotate_array	(char*,int) ;
 void print_permutations(char*,int) ;

 // Max Number Of Elements

 const int MAX_LEN = 10;

 // The Counter

 int counter = 0; 

 // Prints the different permutations of the array of elements
 // recursively.

 void print_permutations(char *array,int pos)
 {	char store[MAX_LEN]; // 
	strcpy(store,array); // Save the array

	for(int i=pos;i<strlen(array);++i)
	{	rotate_array(array,pos); // Rotate the array
		if(pos==strlen(array)-1)
		{	cout<<array<<endl;
			counter++;	 // Inc the counter
		}

		// call print_perm.. recursively

		if((pos+1)<strlen(array)) 		
		print_permutations(array,pos+1); 
	}	
	
	strcpy(array,store); // Restore the array
 }
 
 int main(int argc,char *argv[])
 {	if(argc>1)
	{	print_permutations(argv[1],0);
		cout<<endl<<"Number of permutations = "<<counter<<endl;
	}
	else
		cout<<argv[0]<<" <elements for eg 1234.. or abcd...> ";
 }

 //
 // This function rotates a part of the array
 //

 void rotate_array(char *array, int pos)
 {	char temp = array[pos];	
	for(int i=pos;i<strlen(array);++i)
	{	char temp2 = array[i+1];
		array[i+1] = temp;
		temp = temp2     ;
	}
	array[pos] = array[strlen(array)-1];
	array[strlen(array)-1] = 0;
 }