1 files changed, 60 insertions, 0 deletions
diff --git a/2020/02/solve.c b/2020/02/solve.c
new file mode 100644
index 0000000..6294771
--- /dev/null
+++ b/2020/02/solve.c
@@ -0,0 +1,60 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+int part_one(FILE *fp)
+{
+	int res = 0;
+
+	char *line = NULL;
+	size_t len = 0;
+	while (getline(&line, &len, fp) != -1) {
+		int low, high, cnt = 0;
+		char ch;
+		char str[42];
+		sscanf(line, "%d-%d %c: %s\n", &low, &high, &ch, &str[0]);
+
+		for (char *p = str; *p; p++)
+			if (*p == ch)
+				cnt++;
+
+		if (cnt >= low && cnt <= high)
+			res++;
+	}
+
+	return res;
+}
+
+int part_two(FILE *fp)
+{
+	int res = 0;
+
+	char *line = NULL;
+	size_t len = 0;
+	while (getline(&line, &len, fp) != -1) {
+		int low, high, cnt = 0;
+		char ch, first, second;
+		char str[256];
+		sscanf(line, "%d-%d %c: %s\n", &low, &high, &ch, &str[0]);
+		first = str[low - 1];
+		second = str[high - 1];
+		if (first == ch && second != ch || first != ch && second == ch)
+			res++;
+	}
+
+	return res;
+}
+
+int main(int argc, char *argv[])
+{
+	FILE *fp = fopen("input", "r");
+	if (!fp)
+		exit(EXIT_FAILURE);
+
+	printf("%d\n", part_one(fp));
+	rewind(fp);
+	printf("%d\n", part_two(fp));
+
+	fclose(fp);
+	return 0;
+}