kk

3 files changed, 88 insertions, 0 deletions

diff --git a/2021/17/Makefile b/2021/17/Makefile
new file mode 100644
index 0000000..4a881b7
--- /dev/null
+++ b/2021/17/Makefile
@@ -0,0 +1,19 @@
+DEBUG = -Wno-error -Og -g -s -fsanitize=undefined -fsanitize=address -fstack-protector-all
+CFLAGS = -Wall -Wextra -Werror -Wshadow -Wpointer-arith -Wwrite-strings -Wredundant-decls -Wnested-externs -Wformat=2 -Wmissing-declarations -Wstrict-prototypes -Wmissing-prototypes -Wcast-qual -Wswitch-default -Wswitch-enum -Wunreachable-code -Wundef -Wold-style-definition -Wvla -pedantic-errors -Ofast
+
+# Not the best makefile but idc
+
+debug:
+	@gcc $(CFLAGS) $(DEBUG) solve.c -o solve.o -L/usr/lib -lcrypto
+
+build:
+	@gcc $(CFLAGS) solve.c -o solve.o -L/usr/lib -lcrypto
+
+clean:
+	@rm -f *.o
+
+run: debug
+	@./solve.o
+
+time: build
+	@./solve.o
diff --git a/2021/17/input b/2021/17/input
new file mode 100644
index 0000000..52bdf2b
--- /dev/null
+++ b/2021/17/input
@@ -0,0 +1 @@
+target area: x=175..227, y=-134..-79
diff --git a/2021/17/solve.c b/2021/17/solve.c
new file mode 100644
index 0000000..9d7ba51
--- /dev/null
+++ b/2021/17/solve.c
@@ -0,0 +1,68 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+typedef struct {
+	int x, y;
+} vec2;
+
+typedef struct {
+	vec2 min;
+	vec2 max;
+} range;
+
+#define IN_RANGE(pos, range)                                                                       \
+	(pos.x >= range.min.x && pos.x <= range.max.x && pos.y >= range.min.y &&                   \
+	 pos.y <= range.max.y)
+#define ADD(a, b) (a = (vec2){ a.x + b.x, a.y + b.y })
+#define DRAG(x) ((x) < 0 ? (x)++ : (x) > 0 ? (x)-- : (x))
+
+static int hits(vec2 velocity, range target)
+{
+	vec2 pos = { 0 };
+	while (ADD(pos, velocity), DRAG(velocity.x), velocity.y--, pos.y >= target.min.y)
+		if (IN_RANGE(pos, target))
+			return 1; // Hit!
+	return 0;
+}
+
+static void solve(FILE *fp)
+{
+	int first = 0, second = 0;
+
+	range target;
+	fscanf(fp, "target area: x=%d..%d, y=%d..%d\n", &target.min.x, &target.max.x, &target.min.y,
+	       &target.max.y);
+
+	vec2 velocity;
+	for (velocity.y = target.min.y; velocity.y <= -target.min.y; velocity.y++) {
+		for (velocity.x = 0; velocity.x <= target.max.x; velocity.x++) {
+			if (hits(velocity, target)) {
+				second++;
+				int height = velocity.y * (velocity.y + 1) / 2;
+				if (height > first)
+					first = height;
+			}
+		}
+	}
+
+	printf("%d\n%d\n", first, second);
+}
+
+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;
+}