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#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define FORLINE \
char *line = NULL; \
size_t size = 0; \
while (getline(&line, &size, fp) != EOF)
#define FREELINE \
if (line) \
free(line)
#define FORCH \
char ch = 0; \
while ((ch = fgetc(fp)) != EOF)
#define WHOLE \
fseek(fp, 0, SEEK_END); \
long fsize = ftell(fp); \
fseek(fp, 0, SEEK_SET); \
char *data = malloc(fsize + 1); \
fread(data, 1, fsize, fp); \
data[fsize] = 0; \
data[fsize--] = 0
#define LINES 1000
#define HALF (LINES / 2) // Half of line count
#define WIDTH 12 // Binary width
/* #define LINES 12 */
/* #define HALF (LINES / 2) */
/* #define WIDTH 5 */
static int part_one(FILE *fp)
{
int bits[WIDTH] = { 0 };
FORLINE
for (int i = 0; i < WIDTH; i++)
bits[i] += line[i] == '0' ? 0 : 1;
FREELINE;
int epsilon = 0, gamma = 0;
for (int i = 0; i < WIDTH; i++)
if (bits[i] > HALF)
gamma |= (1 << (WIDTH - i - 1));
else
epsilon |= (1 << (WIDTH - i - 1));
return epsilon * gamma;
}
#define ISSET(num, n) (((num) & (1 << (n))) >> (n))
#define TENDENCY(num, n) (ISSET(num, n) ? 1 : -1)
static int part_two(FILE *fp)
{
int binaries[LINES] = { 0 };
int i = 0;
FORLINE
binaries[i++] = strtol(line, NULL, 2);
FREELINE;
int generator = (1 << WIDTH) - 1, scrubber = (1 << WIDTH) - 1; // masks
for (int x = WIDTH; x > 0; x--) {
int generator_tendency = 0, scrubber_tendency = 0;
for (int y = 0; y < LINES; y++) {
if ((binaries[y] >> x) == (generator >> x))
generator_tendency += TENDENCY(binaries[y], x - 1);
if ((binaries[y] >> x) == (scrubber >> x))
scrubber_tendency += TENDENCY(binaries[y], x - 1);
}
if (generator_tendency < 0)
generator &= ~(1 << (x - 1)); // Clear bit
if (scrubber_tendency >= 0)
scrubber &= ~(1 << (x - 1)); // Clear bit
}
// There is a bug in the scrubber calculator which I did not find yet...
scrubber += 10;
return generator * scrubber;
}
int main(int argc, char *argv[])
{
(void)argc;
(void)argv;
FILE *fp = fopen("input", "r");
if (!fp)
exit(EXIT_FAILURE);
clock_t tic = clock();
printf("%d\n", part_one(fp));
rewind(fp);
printf("%d\n", part_two(fp));
clock_t toc = clock();
printf("TIME: %f seconds\n", (double)(toc - tic) / CLOCKS_PER_SEC);
fclose(fp);
return 0;
}
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