4 files changed, 120 insertions, 0 deletions
diff --git a/2020/17/.gitignore b/2020/17/.gitignore
new file mode 100644
index 0000000..60d075d
--- /dev/null
+++ b/2020/17/.gitignore
@@ -0,0 +1 @@
+puzzle-[12]
diff --git a/2020/17/Makefile b/2020/17/Makefile
new file mode 100644
index 0000000..c32dafa
--- /dev/null
+++ b/2020/17/Makefile
@@ -0,0 +1,7 @@
+all:
+	${CC} ${CFLAGS} -o puzzle-1 puzzles.c
+	${CC} ${CFLAGS} -DPART2 -o puzzle-2 puzzles.c
+
+.PHONY: clean
+clean:
+	rm -f puzzle-[12]
diff --git a/2020/17/input b/2020/17/input
new file mode 100644
index 0000000..3b42c23
--- /dev/null
+++ b/2020/17/input
@@ -0,0 +1,8 @@
+...#..#.
+.....##.
+##..##.#
+#.#.##..
+#..#.###
+...##.#.
+#..##..#
+.#.#..#.
+\ No newline at end of file
diff --git a/2020/17/puzzles.c b/2020/17/puzzles.c
new file mode 100644
index 0000000..4e98982
--- /dev/null
+++ b/2020/17/puzzles.c
@@ -0,0 +1,104 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* PART2 is defined for part 2, but not for part 1 */
+#ifdef PART2
+	#define MAXTIME 50
+#else
+	#define MAXTIME 1
+#endif
+#define MAXDEPTH  50
+#define MAXHEIGHT 50
+#define MAXWIDTH  50
+
+char space[MAXTIME][MAXDEPTH][MAXHEIGHT][MAXWIDTH];
+char temp[MAXTIME][MAXDEPTH][MAXHEIGHT][MAXWIDTH];
+
+/* Check the cubes around the given coordinates and update the temp array accordingly */
+static void
+update_cube(unsigned int const t, unsigned int const i, unsigned int const j, unsigned int const k)
+{
+	unsigned int active = 0;
+
+	for (int tme = t - 1; tme <= (int) t + 1; tme++) {
+		if (tme < 0 || tme > MAXTIME - 1)
+			continue;
+		for (int dep = i - 1; dep <= (int) i + 1; dep++) {
+			if (dep < 0 || dep > MAXDEPTH - 1)
+				continue;
+			for (int hgt = j - 1; hgt <= (int) j + 1; hgt++) {
+				if (hgt < 0 || hgt > MAXHEIGHT - 1)
+					continue;
+				for (int wid = k - 1; wid <= (int) k + 1; wid++) {
+					if (wid < 0 || wid > MAXWIDTH - 1
+					    || (tme == (int) t && dep == (int) i && hgt == (int) j
+					        && wid == (int) k))
+						continue;
+
+					if (space[tme][dep][hgt][wid] == '#')
+						active++;
+				}
+			}
+		}
+	}
+
+	if (space[t][i][j][k] == '#' && (active == 2 || active == 3))
+		temp[t][i][j][k] = '#';
+	else if (space[t][i][j][k] == '.' && active == 3)
+		temp[t][i][j][k] = '#';
+	else
+		temp[t][i][j][k] = '.';
+}
+
+int
+main(void)
+{
+	/* Initialze space */
+	memset(space, '.', MAXTIME * MAXDEPTH * MAXHEIGHT * MAXWIDTH);
+
+	/* Read input */
+	FILE *fpt = fopen("input", "r");
+	char c;
+	unsigned int t, i, j, k;
+
+	j = k = 0;
+	while ((c = fgetc(fpt)) != EOF) {
+		if (c == '\n') {
+			j++;
+			k = 0;
+		}
+		else {
+			space[MAXTIME / 2][MAXDEPTH / 2][j + MAXHEIGHT / 2][k + MAXWIDTH / 2] = c;
+			k++;
+		}
+	}
+
+	/* Do the boot cycles */
+	for (int cycle = 0; cycle < 6; cycle++) {
+		for (t = 0; t < MAXTIME; t++)
+			for (i = 0; i < MAXDEPTH; i++)
+				for (j = 0; j < MAXHEIGHT; j++)
+					for (k = 0; k < MAXWIDTH; k++)
+						update_cube(t, i, j, k);
+
+		/* Copy temp to space */
+		for (t = 0; t < MAXTIME; t++)
+			for (i = 0; i < MAXDEPTH; i++)
+				for (j = 0; j < MAXHEIGHT; j++)
+					for (k = 0; k < MAXWIDTH; k++)
+						space[t][i][j][k] = temp[t][i][j][k];
+	}
+
+	/* Count the active cubes */
+	unsigned int count = 0;
+	for (t = 0; t < MAXTIME; t++)
+		for (i = 0; i < MAXDEPTH; i++)
+			for (j = 0; j < MAXHEIGHT; j++)
+				for (k = 0; k < MAXWIDTH; k++)
+					if (space[t][i][j][k] == '#')
+						count++;
+
+	printf("%u\n", count);
+	return EXIT_SUCCESS;
+}