ez

1 files changed, 84 insertions, 0 deletions

diff --git a/2021/20/solve.c b/2021/20/solve.c
new file mode 100644
index 0000000..96ece6b
--- /dev/null
+++ b/2021/20/solve.c
@@ -0,0 +1,84 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#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;
+
+#define SIZE 100
+#define MULTI (SIZE + 10) // idk
+#define LINE (SIZE + 1)
+#define GET(x, y) image[(y) * (SIZE + MULTI) + (x)]
+static void solve(FILE *fp)
+{
+	WHOLE;
+
+	char buff[(SIZE + MULTI) * (SIZE + MULTI)];
+	char image[(SIZE + MULTI) * (SIZE + MULTI)];
+	for (int y = 0; y < SIZE; y++)
+		for (int x = 0; x < SIZE; x++)
+			buff[(y + MULTI / 2) * (SIZE + MULTI) + (x + MULTI / 2)] =
+				data[514 + (y * LINE + x)];
+
+	int offset = 1;
+
+aah:;
+	memset(image, offset % 2 == 0 ? '#' : '.', sizeof(image)); // Due to alg[0]
+	for (int y = MULTI / 2 - offset + 1; y < SIZE + MULTI / 2 + offset - 1; y++)
+		for (int x = MULTI / 2 - offset + 1; x < SIZE + MULTI / 2 + offset - 1; x++)
+			image[y * (SIZE + MULTI) + x] = buff[y * (SIZE + MULTI) + x];
+
+	for (int y = MULTI / 2 - offset; y < SIZE + MULTI / 2 + offset; y++) {
+		for (int x = MULTI / 2 - offset; x < SIZE + MULTI / 2 + offset; x++) {
+			int algorithm = ((GET(x - 1, y - 1) == '#') << 8) |
+					((GET(x - 0, y - 1) == '#') << 7) |
+					((GET(x + 1, y - 1) == '#') << 6) |
+					((GET(x - 1, y - 0) == '#') << 5) |
+					((GET(x - 0, y - 0) == '#') << 4) |
+					((GET(x + 1, y - 0) == '#') << 3) |
+					((GET(x - 1, y + 1) == '#') << 2) |
+					((GET(x - 0, y + 1) == '#') << 1) |
+					((GET(x + 1, y + 1) == '#') << 0);
+
+			buff[y * (SIZE + MULTI) + x] = data[algorithm];
+		}
+	}
+
+	if (offset == 2 || offset == 50) {
+		int res = 0;
+		for (unsigned int i = 0; i < sizeof(buff); i++)
+			if (buff[i] == '#')
+				res++;
+		printf("%d\n", res);
+	}
+	if (offset == 50) {
+		free(data);
+		return;
+	}
+	offset++;
+	goto aah;
+}
+
+int main(int argc, char *argv[])
+{
+	(void)argc;
+	(void)argv;
+
+	FILE *fp = fopen("input", "r");
+	if (!fp)
+		exit(EXIT_FAILURE);
+
+	clock_t tic = clock();
+	solve(fp);
+	clock_t toc = clock();
+	printf("TIME: %f seconds\n", (double)(toc - tic) / CLOCKS_PER_SEC);
+
+	fclose(fp);
+	return 0;
+}