From 3bc9b83494916ed3928556dae7773664e70c6f21 Mon Sep 17 00:00:00 2001
From: Tomasz Kramkowski <tomasz@kramkow.ski>
Date: Sat, 2 Dec 2023 22:35:29 +0000
Subject: day 2 in C

---
 2.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 2.c

(limited to '2.c')

diff --git a/2.c b/2.c
new file mode 100644
index 0000000..1edf10c
--- /dev/null
+++ b/2.c
@@ -0,0 +1,92 @@
+#include <stdio.h>
+#include <ctype.h>
+#include <assert.h>
+#include <stdbool.h>
+
+struct counts {
+	int red, green, blue;
+};
+
+int main(void)
+{
+	static const struct counts limits = { 12, 13, 14 };
+	bool possible = false;
+	int c, id = -1, count = -1, p1 = 0, p2 = 0;
+	struct counts counts, max;
+	enum state {
+		START,
+		GAME_ID,
+		CUBE_COUNT,
+		CUBE_SPACE,
+		CUBE_COLOUR,
+		CUBE_SEP,
+		SUBSET_SEP,
+	} state = START;
+	while (c = getchar(), c != EOF) {
+		enum state prev = state;
+		switch (state) {
+		case START:
+			if (isdigit(c)) state = GAME_ID;
+			break;
+		case GAME_ID:
+			if (!isdigit(c)) state = SUBSET_SEP;
+			break;
+		case CUBE_COUNT:
+			if (!isdigit(c)) state = CUBE_SPACE;
+			break;
+		case CUBE_SPACE:
+			if (isalpha(c)) state = CUBE_COLOUR;
+			break;
+		case CUBE_COLOUR:
+			switch (c) {
+			case ',':  state = CUBE_SEP;   break;
+			case ';':  state = SUBSET_SEP; break;
+			case '\n': state = START;      break;
+			}
+			break;
+		case SUBSET_SEP:
+		case CUBE_SEP:
+			if (isdigit(c)) state = CUBE_COUNT;
+			break;
+		}
+		if (prev == START && state == GAME_ID) {
+			id = 0;
+			max = (struct counts){0, 0, 0};
+			possible = true;
+		}
+		if (state == GAME_ID) {
+			id *= 10;
+			id += c - '0';
+		}
+		if (prev == SUBSET_SEP && state == CUBE_COUNT)
+			counts = (struct counts){0, 0, 0};
+		if (prev != CUBE_COUNT && state == CUBE_COUNT)
+			count = 0;
+		if (state == CUBE_COUNT) {
+			count *= 10;
+			count += c - '0';
+		}
+		if (prev == CUBE_SPACE && state == CUBE_COLOUR) {
+			switch (c) {
+			case 'r': counts.red   = count; break;
+			case 'g': counts.green = count; break;
+			case 'b': counts.blue  = count; break;
+			default: assert(false && "Unexpected colour"); break;
+			}
+		}
+		if (prev == CUBE_COLOUR && (state == SUBSET_SEP || state == START)) {
+			if (counts.red   > max.red)   max.red   = counts.red;
+			if (counts.green > max.green) max.green = counts.green;
+			if (counts.blue  > max.blue)  max.blue  = counts.blue;
+			if (counts.red   > limits.red   ||
+			    counts.green > limits.green ||
+			    counts.blue  > limits.blue)
+				possible = false;
+		}
+		if (prev != START && state == START) {
+			if (possible) p1 += id;
+			p2 += max.red * max.green * max.blue;
+		}
+	}
+	printf("%d\n%d\n", p1, p2);
+}
-- 
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