#include "Header.h"

typedef struct
{
	int char1;
	int char2;
	long count;
} CharPair;

int compare (const void * a, const void * b)
{
	return ((*((CharPair *) b)).count - (*((CharPair *) a)).count );
}

void printResult(const void * a)
{
	int i;
	CharPair *pairs = (CharPair *) a;
	//print Report
	for(i = 0; i < NOut; i++)
	{
		printf("(%c,%-c)  %-10d\n", (unsigned char)pairs[i].char1,
			(unsigned char)pairs[i].char2, pairs[i].count);
	}
}

void countPairs()
{
	//char pair
	CharPair charPair[256][256];
	unsigned char charBuffer[NMax];
	int i, j, charRead;
	int firstChar, secondChar;
	
	//initilize array items to zero
	for(i = 0; i < 256; i++)
	{
		for(j = 0; j < 256; j++)
		{
			charPair[i][j].char1 = i;
			charPair[i][j].char2 = j;
			charPair[i][j].count = 0;
		}
	}
	
	//read the first bunch
	if((charRead = fread(charBuffer, sizeof(unsigned char), NMax, stdin)) != EOF)
	{
		firstChar = abs(charBuffer[0]);
		for(i =1; i < charRead; i++)
		{
			secondChar = abs(charBuffer[i]);
			charPair[firstChar][secondChar].count += 1;
			firstChar = secondChar;
		}
	}
	//read chars in bunches of NMax
	while(charRead = fread(charBuffer, sizeof(unsigned char), NMax, stdin))
	{
		for(i =0; i < charRead; i++)
		{
			secondChar = abs(charBuffer[i]);
			charPair[firstChar][secondChar].count += 1;
			firstChar = secondChar;
		}
	}
	
	//sort array
	qsort (charPair, 65536, sizeof(CharPair), compare);
	
	//print result
	printResult(charPair);
}