muahahaha

1 files changed, 81 insertions, 0 deletions

diff --git a/2021/05/solve.c b/2021/05/solve.c
new file mode 100644
index 0000000..b0f6777
--- /dev/null
+++ b/2021/05/solve.c
@@ -0,0 +1,81 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#define FORLINE                                                                                    \
+	char *line = NULL;                                                                         \
+	size_t len = 0;                                                                            \
+	while (getline(&line, &len, fp) != EOF)
+#define FREELINE                                                                                   \
+	if (line)                                                                                  \
+	free(line)
+
+#define SIZE 1024
+static void solve(FILE *fp)
+{
+	int one = 0, two = 0; // Parts
+
+	int *straight = calloc(4, SIZE * SIZE);
+	int *diagonal = calloc(4, SIZE * SIZE);
+
+	FORLINE
+	{
+		int x1, y1, x2, y2;
+		sscanf(line, "%d,%d -> %d,%d\n", &x1, &y1, &x2, &y2);
+
+		int xstart = x1 <= x2 ? x1 : x2;
+		int xend = x1 >= x2 ? x1 : x2;
+
+		if (x1 == x2 || y1 == y2) { // Straight
+			int ystart = y1 <= y2 ? y1 : y2;
+			int yend = y1 >= y2 ? y1 : y2;
+
+			for (int y = ystart; y <= yend; y++) {
+				for (int x = xstart; x <= xend; x++) {
+					straight[y * SIZE + x]++;
+					diagonal[y * SIZE + x]++;
+				}
+			}
+		} else { // Diagonal
+			int xneg = x1 > x2 ? -1 : 1;
+			int yneg = y1 > y2 ? -1 : 1;
+			for (int a = 0; xstart + a <= xend; a++)
+				diagonal[(y1 + a * yneg) * SIZE + (x1 + a * xneg)]++;
+		}
+	}
+	FREELINE;
+
+	for (int y = 0; y < SIZE; y++) {
+		for (int x = 0; x < SIZE; x++) {
+			if (straight[y * SIZE + x] >= 2)
+				one++;
+			if (diagonal[y * SIZE + x] >= 2)
+				two++;
+		}
+	}
+
+	free(straight);
+	free(diagonal);
+
+	printf("%d\n", one);
+	printf("%d\n", two);
+}
+
+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;
+}