Fixed naming for 10+ challenges

1 files changed, 103 insertions, 0 deletions

diff --git a/2020/05/solve.c b/2020/05/solve.c
new file mode 100644
index 0000000..025b644
--- /dev/null
+++ b/2020/05/solve.c
@@ -0,0 +1,103 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#define COUNT 1024
+#define FIRST 100
+#define LAST 1000
+
+int row(char *s)
+{
+	int low = 0;
+	int high = 128;
+	for (char *p = s; *p && *p != 'R' && *p != 'L'; p++) {
+		if (*p == 'F') {
+			high -= 2 << (5 - (p - s));
+		} else if (*p == 'B') {
+			low += 2 << (5 - (p - s));
+		}
+	}
+	return low;
+}
+
+int col(char *s)
+{
+	int low = 0;
+	int high = 8;
+	for (char *p = s + 7; *(p + 1); p++) {
+		if (*p == 'L') {
+			high -= 2 << (1 - (p - (s + 7)));
+		} else if (*p == 'R') {
+			low += 2 << (1 - (p - (s + 7)));
+		}
+	}
+	if (*(s + 9) == 'R')
+		return high - 1;
+	else if (*(s + 9) == 'L')
+		return low;
+	else
+		return 0;
+}
+
+int compare(const void *a, const void *b)
+{
+	int int_a = *((int *)a);
+	int int_b = *((int *)b);
+
+	if (int_a == int_b)
+		return 0;
+	else if (int_a < int_b)
+		return -1;
+	else
+		return 1;
+}
+
+static int ids[COUNT] = { 0 };
+
+int part_one(FILE *fp)
+{
+	int res = 0;
+
+	char *line = NULL;
+	size_t len = 0;
+	int i = 0;
+	while (getline(&line, &len, fp) != -1) {
+		int id = row(line) * 8 + col(line);
+		if (id > res)
+			res = id;
+
+		ids[i] = id;
+		i++;
+	}
+
+	return res;
+}
+
+int part_two()
+{
+	int res = 0;
+
+	qsort(ids, COUNT, sizeof(int), compare);
+
+	for (int i = 1; i < COUNT - 1; ++i) {
+		if (ids[i] == 0)
+			continue;
+
+		if (ids[i] != ids[i + 1] && ids[i] != ids[i - 1] && i > FIRST && i < LAST)
+			res = ids[i];
+	}
+
+	return res;
+}
+
+int main(int argc, char *argv[])
+{
+	FILE *fp = fopen("input", "r");
+	if (!fp)
+		exit(EXIT_FAILURE);
+
+	printf("%d\n", part_one(fp));
+	printf("%d\n", part_two());
+
+	fclose(fp);
+	return 0;
+}