Printing powerset for given set of characters.

Printing powerset of characters is somewhat easy. Here the key point is to understand that for a given number of n characters we will have (2^N)-1 combinations. We will then count thru integers starting from 1 to (2^N)-1 and then check the bit set on the integer and accordingly the same element will be printed from the character array. Below is the C implementation of this interesting program :

	/*
	* Combinatorial.cpp
	*
	* Created on: Dec 6, 2014
	* Author: prasadnair
	*/
	#include <stdio.h>
	#include <math.h>
	void printPowerSet(char *, int );
	/*Driver program to test printPowerSet*/
	int main()
	{
	char set[] = {'a','b','c', 'd'};
	printPowerSet(set, 4);
	getchar();
	return 0;
	}
	void printPowerSet(char *set, int set_size)
	{
	/*set_size of power set of a set with set_size
	n is (2**n -1)*/
	unsigned int pow_set_size = pow((float)2, set_size);
	int counter, j;
	/*Run from counter 000..0 to 111..1*/
	for(counter = 0; counter < pow_set_size; counter++)
	{
	for(j = 0; j < set_size; j++)
	{
	/* Check if jth bit in the counter is set
	If set then print jth element from set */
	if(counter & (1<<j))
	printf("%c", set[j]);
	}
	printf("\n");
	}
	}

view raw PowerSet.c hosted with ❤ by GitHub