Puzzle 3: Consolidate 3a/3b programs into `3` with `-p` option

Like the later puzzles

1 files changed, 163 insertions, 0 deletions

diff --git a/3.c b/3.c
new file mode 100644
index 0000000..6cb68db
--- /dev/null
+++ b/3.c
@@ -0,0 +1,163 @@
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+int
+chrcmp(void const * a, void const * b)
+{
+	return (*(char const *) a) - *((char const *) b);
+}
+
+
+int
+priority(int c)
+{
+	if (c >= 'A' && c <= 'Z')
+		return 27 + c - 'A';
+	if (c >= 'a' && c <= 'z')
+		return 1 + c - 'a';
+	fprintf(stderr, "Unexpected priority request: %c\n", c);
+	return -1;
+}
+
+
+int
+min(int a, int b)
+{
+	return a < b ? a : b;
+}
+
+
+int
+min3(int a, int b, int c)
+{
+	return min(min(a, b), c);
+}
+
+
+int
+rucksack_common_sum()
+{
+	char buf[BUFSIZ];
+	int score = 0;
+
+	while (fgets(buf, sizeof(buf), stdin)) {
+		int len, i, j;
+
+		len = strlen(buf);
+		if (len && buf[len - 1] == '\n')
+			--len;
+		if (len % 2 == 1) {
+			fprintf(stderr, "Unexpected length: %d\n", len);
+			return -1;
+		}
+
+		qsort(buf, len / 2, 1, chrcmp);
+		qsort(buf + len / 2, len / 2, 1, chrcmp);
+
+		i = 0;
+		j = len / 2;
+		while (i < len / 2 && j < len) {
+			if (buf[i] < buf[j])
+				++i;
+			else if (buf[j] < buf[i])
+				++j;
+			else
+				break;
+		}
+		if (i >= len / 2 || j >= len) {
+			fprintf(stderr, "No match found in %s\n", buf);
+			return -1;
+		}
+		score += priority(buf[i]);
+	}
+
+	return score;
+}
+
+
+int
+group_badge_sum()
+{
+	char buf[3][BUFSIZ];
+	int score = 0;
+
+	while (fgets(buf[0], sizeof(buf[0]), stdin)
+			&& fgets(buf[1], sizeof(buf[1]), stdin)
+			&& fgets(buf[2], sizeof(buf[2]), stdin))
+	{
+		int n, i, j, k;
+
+		for (n = 0; n < 3; ++n) {
+			int len = strlen(buf[n]);
+			if (len && buf[n][len - 1] == '\n') {
+				--len;
+				buf[n][len] = '\0';
+			}
+			if (len % 2 == 1) {
+				fprintf(stderr, "Unexpected length: %d\n", len);
+				return -1;
+			}
+
+			qsort(buf[n], len, 1, chrcmp);
+		}
+
+		i = 0; j = 0; k = 0;
+		while (buf[0][i] != '\0' && buf[1][j] != '\0' && buf[2][k] != '\0') {
+			int n = min3(buf[0][i], buf[1][j], buf[2][k]);
+			if (buf[0][i] == n && buf[1][j] == n && buf[2][k] == n)
+				break;
+			if (buf[0][i] == n)
+				++i;
+			if (buf[1][j] == n)
+				++j;
+			if (buf[2][k] == n)
+				++k;
+		}
+		if (buf[0][i] == '\0' || buf[1][j] == '\0' || buf[2][k] == '\0') {
+			fprintf(stderr, "No match found in %s/%s/%s\n", buf[0], buf[1], buf[2]);
+			return -1;
+		}
+		score += priority(buf[0][i]);
+	}
+
+	return score;
+}
+
+
+int
+main(int argc, char ** argv)
+{
+	int part = 1, i;
+
+	while ((i = getopt(argc, argv, "p:")) != -1) {
+		switch (i) {
+		case 'p':
+			part = atoi(optarg);
+			break;
+
+		default:
+			return -1;
+		}
+	}
+
+	switch (part) {
+	case 1:
+		printf("Score: %d\n", rucksack_common_sum());
+		break;
+
+	case 2:
+		printf("Score: %d\n", group_badge_sum());
+		break;
+
+	default:
+		fprintf(stderr, "Unexpected puzzle part %d\n", part);
+		return -1;
+	}
+
+	return 0;
+}
+