/*  Run-length Encoding (15 points)

 "Run-length encoding (RLE) is a very simple form of data compression in which 
 runs of data (that is, sequences in which the same data value occurs in many 
 consecutive data elements) are stored as a single data value and a count, rather 
 than as the original run. This is most useful on data that contains many such runs; 
 for example, simple graphic images such as icons and line drawings. For example, 
 consider a screen containing plain black text on a solid white background. There 
 will be many long runs of white pixels in the blank space, and many short runs of 
 black pixels within the text." (Source: Wikipedia)
 
 
 As an example, consider this scan line, where 0 represents a black pixel 
 and 1 represents a white pixel:  00111000110111100001
 
 If apply the run-length encoding algorithm to that scan line, 
 then we will get the following encoded result: 2B3W3B2W1B4W4B1W
 
 Interpret this as 2 Black pixels, 3 White pixels, 3 Black pixels, etc. 
 
 Write a complete C program that reads a line of 20 pixels from the user
 (represented with 0's and 1's), encodes them using run-length encoding, 
 and prints the encoding on the screen.  Sample runs are shown below.
 
 ============= START OF SAMPLE RUN =======================
 Original:  00001110111111100001
 Encoded:   4B3W1B7W4B1W
 =============  END OF SAMPLE RUN  =======================
 
 
 ============= START OF SAMPLE RUN =======================
 Original:  11110011000011100000
 Encoded:   4W2B2W4B3W5B
 =============  END OF SAMPLE RUN  =======================
 
 
 
 ============= START OF SAMPLE RUN =======================
 Original:  01001100011100001111
 Encoded:   1B1W2B2W3B3W4B4W
 =============  END OF SAMPLE RUN  =======================
 
 
 
 ============= START OF SAMPLE RUN =======================
 Original:  11111100101001100000
 Encoded:   6W2B1W1B1W2B2W5B
 =============  END OF SAMPLE RUN  =======================
 
 
 
 ============= START OF SAMPLE RUN =======================
 Original:  10101010101010101010
 Encoded:   1W1B1W1B1W1B1W1B1W1B1W1B1W1B1W1B1W1B1W1B
 =============  END OF SAMPLE RUN  =======================
 
*/

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

#define DEBUG 0


int main()
{
	int a[20];
	char ch;
	int i;
	
		
	printf("Original: ");
	for(i=0; i<20; i++)
	{
		scanf("%c", &ch);
		a[i]= (int)(ch-'0');
	}
		
	// create a random array
	//srand(time(NULL));
	//for(i=0; i<20; i++)
	//	a[i]=rand()%2;
		
	// print the original array
	if(DEBUG)
	{
		printf("Original: ");
		for(i=0; i<20; i++)
			printf("%c", a[i]+'0');
		printf("\n\n");
	}
	
	// use a temporary array count; zero it first
	int count[20];
	for(i=0; i<20; i++)
		count[i]=0;
		
	int n=0;
	i=0;
	
	do
	{
		count[n]=1;
		
		while( (a[i] == a[i+1]) && (i<20) )
		{
			count[n]++;
			i++;
		}
		
		n++;
		i++;
		
	}while(i<20);
	
	// print the count array
	char c;
	
	if(a[0]== 0)
		c='B';
	else 
		c='W';
	
	
	printf("Encoded:  ");
	for(i=0; i<n; i++)
	{
		printf("%d%c", count[i],c);
		if(c=='B') // change the value of c for the next iteration
			c='W';
		else
			c='B';
	}
		
	printf("\n");
	
	system("pause");
}