Advent-of-Code/2021/day14/solution-part2.c

#include <stdio.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>

#define ANSI_COLOR_RED     "\x1b[31m"
#define ANSI_COLOR_YELLOW  "\x1b[33m"
#define ANSI_COLOR_RESET   "\x1b[0m"

#define MAX(a, b) ((a) < (b) ? (b) : (a))
#define MIN(a, b) ((a) < (b) ? (a) : (b))

#define pairId(a,b) ( (26 * ( a - 'A' )) + ( b - 'A' ) )

typedef struct Interaction Interaction;
struct Interaction{
	char letter1;
	char letter2;
	char result;
	Interaction *next;
};


Interaction* newInteraction(char letter1, char letter2, char result){
	Interaction *new = malloc(sizeof(Interaction));
	new->letter1 = letter1;
	new->letter2 = letter2;
	new->result = result;
	new->next = NULL;
	return new;
}

void printElementPairs(unsigned long *pairs){
	for ( unsigned int i = 'A'; i <= 'Z'; i++ )
		for ( unsigned int j = 'A'; j <= 'Z'; j++ ){
			if ( pairs[pairId(i,j)] > 0 ) printf("%c%c: %lu\n", i, j, pairs[pairId(i,j)]);
		}
}

void printElements(unsigned long *letters){
	for ( unsigned int i = 'A'; i <= 'Z'; i++ )
		if ( letters[i-'A'] > 0 ) printf("%c: %lu\n", i, letters[i-'A']);
}

void printInteractions(Interaction *current){
	while ( current != NULL ){
		printf("Merging %c and %c will give you %c\n",current->letter1, current->letter2, current->result);
		current = current->next;
	}
	printf("\n");
}


char interact(char firstCh, char secondCh, Interaction *interaction){
	while ( interaction != NULL ){
		if ( interaction->letter1 == firstCh && interaction->letter2 == secondCh )
			return interaction->result;
		interaction = interaction->next;
	}
	return 0;
}

unsigned long calculateScore(unsigned long *letters){
	unsigned long min = ~0;
	unsigned long max = 0;
	for ( unsigned int i = 0; i < 26; i++ ){
		unsigned long count = letters[i];
		if ( count > 0 ){
			min = MIN( min, count );
			max = MAX( max, count );
		}
	}
	printf("Max: %lu, Min: %lu, Difference: %lu\n", max, min, max-min);
	return 0;
}

unsigned long* step(unsigned long *oldPairsCount, unsigned long *letterCount, Interaction *interaction){
	unsigned long *newPairsCount = malloc( sizeof(long) * ( 1 + pairId('Z','Z') ) );
	memset(newPairsCount, 0,  sizeof(long) * ( 1 + pairId('Z','Z') ) );
	for ( unsigned int i = 'A'; i <= 'Z'; i++ )
		for ( unsigned int j = 'A'; j <= 'Z'; j++ ){
			unsigned long count = oldPairsCount[pairId(i,j)];
			if ( count > 0 ){
				char newChar = interact(i,j,interaction);
				newPairsCount[pairId(i,newChar)] += count;
				newPairsCount[pairId(newChar,j)] += count;
				letterCount[newChar - 'A'] += count;
			}
		}
	free(oldPairsCount);
	return newPairsCount;
}

int main( int argc, char *argv[] ){
	if( argc == 2 ) {


		FILE *fp=fopen(argv[1], "r");

		char line[80];
		unsigned long *pairsCount = malloc( sizeof(long) * ( 1 + pairId('Z','Z') ) );
		memset(pairsCount, 0,  sizeof(long) * ( 1 + pairId('Z','Z') ) );
		unsigned long *letterCount = malloc( sizeof(long) * 26 );
		memset(letterCount, 0,  sizeof(long) * 26 );

		//first line
		fscanf( fp, "%s", line );
		for ( unsigned int i = 0; i < strlen(line); i++ ){
			if ( line[i+1] != '\0' ){
				printf("Pair: %c %c\n", line[i], line[i+1]);
				pairsCount[pairId(line[i], line[i+1])]++;
			}
			letterCount[line[i] - 'A']++;
		}



		//Skip over empty lines
		while( !feof(fp) && fscanf(fp, "\n\n") ) continue;

		char firstCh, secondCh, resultCh;
		Interaction *firstInt = NULL;
		Interaction *previousInt = NULL;
		while( !feof(fp) && fscanf(fp, "%c%c -> %c\n", &firstCh, &secondCh, &resultCh) ){
			if ( firstInt == NULL ){
				firstInt = newInteraction(firstCh, secondCh, resultCh);
				previousInt = firstInt;
			} else {
				previousInt->next = newInteraction(firstCh, secondCh, resultCh);
				previousInt = previousInt->next;
			}
		}

		//printInteractions(firstInt);


		printElementPairs(pairsCount);

		printf("\n\n");

		for ( unsigned int i = 0; i < 40; i++ ){
			printf("\nStep %i:\n", i+1);
			pairsCount = step(pairsCount,letterCount,firstInt);
			printElementPairs(pairsCount);
			printElements(letterCount);
		}

		calculateScore(letterCount);

		fclose(fp);



		return 0;
	} else {
		printf("You need to provide a file\n");
		return 1;
	}
}