136 lines
3.5 KiB
C
136 lines
3.5 KiB
C
#include <stdio.h>
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#include <stdint.h>
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#include <string.h>
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#include <stdlib.h>
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#include <math.h>
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#include "puzzle_input.h"
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#include "day.h"
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#define DIAGNOSTIC_LEN 2000
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#define MAX_WORD_LEN 50
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typedef struct {
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char word[MAX_WORD_LEN];
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uint32_t len;
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} diagnostic_word_t;
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typedef enum {
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OXYGEN = 1,
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CO2 = 0
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} life_support_rating_t;
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parse_ret_t parse_diagnostic_data(char * buffer, void * data, uint16_t index) {
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diagnostic_word_t * diagnostic_data = (diagnostic_word_t *)data;
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diagnostic_data[index].len = strlen(buffer);
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strncpy(diagnostic_data[index].word, buffer, MAX_WORD_LEN);
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return PARSER_OK;
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}
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static void part_1(diagnostic_word_t * diagnostic_data, uint16_t len) {
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uint64_t gamma_rate = 0;
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uint64_t epsilon_rate = 0;
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uint16_t bit_len = diagnostic_data[0].len;
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for (int bit_ndx = 0; bit_ndx < bit_len; bit_ndx++) {
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int32_t one_count = 0;
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for (int word_ndx = 0; word_ndx < len; word_ndx++) {
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if (diagnostic_data[word_ndx].word[bit_ndx] == '1') {
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one_count++;
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}
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}
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if (one_count < len/2) {
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epsilon_rate |= 1 << (bit_len - bit_ndx - 1);
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}
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else {
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gamma_rate |= 1 << (bit_len - bit_ndx - 1);
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}
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}
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printf("PART 1: The power consumption is %lu * %lu = %lu\n", gamma_rate, epsilon_rate, gamma_rate*epsilon_rate);
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}
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int64_t get_rating(diagnostic_word_t * diagnostic_data, uint16_t len, life_support_rating_t mode) {
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uint16_t bit_len = diagnostic_data[0].len;
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uint8_t keep[DIAGNOSTIC_LEN];
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memset(keep, 1, len);
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for (int bit_ndx = 0; bit_ndx < bit_len; bit_ndx++) {
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int32_t one_count = 0;
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int32_t total = 0;
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int32_t keep_1 = 0;
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for (int word_ndx = 0; word_ndx < len; word_ndx++) {
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if (keep[word_ndx]) {
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if (diagnostic_data[word_ndx].word[bit_ndx] == '1') {
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one_count++;
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}
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total++;
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}
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}
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if (total == 1) {
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break;
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}
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if ((float)one_count >= ceil(total/2.0)) {
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keep_1 = mode;
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}
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else {
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keep_1 = !mode;
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}
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for (int word_ndx = 0; word_ndx < len; word_ndx++) {
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if (keep[word_ndx]) {
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if (diagnostic_data[word_ndx].word[bit_ndx] == '1') {
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keep[word_ndx] = keep_1;
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}
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else {
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keep[word_ndx] = !keep_1;
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}
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}
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}
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}
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for (int word_ndx = 0; word_ndx < len; word_ndx++) {
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if (keep[word_ndx]) {
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return strtol(diagnostic_data[word_ndx].word, NULL, 2);
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}
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}
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return -1;
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}
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void part_2(diagnostic_word_t * diagnostic_data, uint16_t len) {
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int64_t oxygen_rating = get_rating(diagnostic_data, len, OXYGEN);
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int64_t co2_rating = get_rating(diagnostic_data, len, CO2);
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printf("PART 2: The life support rating is %ld * %ld = %ld", oxygen_rating, co2_rating, oxygen_rating*co2_rating);
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}
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static diagnostic_word_t diagnostic_data_g[DIAGNOSTIC_LEN];
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int day_3() {
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uint16_t len;
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parse_ret_t parse_ret;
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parse_ret = read_input_single_line("../inputs/day_3.txt", (void *) diagnostic_data_g, DIAGNOSTIC_LEN,
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parse_diagnostic_data, &len);
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if (parse_ret != PARSER_OK) {
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printf("Unable to parse input data: %d", parse_ret);
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return -1;
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}
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part_1(diagnostic_data_g, len);
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part_2(diagnostic_data_g, len);
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return 0;
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} |