1 files changed, 86 insertions, 0 deletions
diff --git a/2021/01/solve.c b/2021/01/solve.c
new file mode 100644
index 0000000..404ba2c
--- /dev/null
+++ b/2021/01/solve.c
@@ -0,0 +1,86 @@
+#include <stdio.h>
+#include <stdlib.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 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
+
+static int part_one(FILE *fp)
+{
+	int res = 0xffffffff;
+
+	int prev = 0;
+	FORLINE
+	{
+		int strength = atoi(line);
+		if (strength > prev)
+			res++;
+		prev = strength;
+	}
+	FREELINE;
+
+	return res;
+}
+
+static int part_two(FILE *fp)
+{
+	int res = 0;
+
+	int prevstrength = -1;
+
+	int prevprev = -1;
+	int prev = -1;
+	FORLINE
+	{
+		int orig = atoi(line);
+		int strength = 0;
+		if (prevprev > 0 && prev > 0)
+			strength = orig + prev + prevprev;
+		if (prevstrength > 0 && strength > prevstrength)
+			res++;
+		prevstrength = strength;
+		prevprev = prev;
+		prev = orig;
+	}
+	FREELINE;
+
+	return res;
+}
+
+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;
+}