AOC2023: implement day7

userspace/aoc2023/CMakeLists.txt

@@ -9,6 +9,7 @@ set(AOC2023_PROJECTS
 	day4
 	day5
 	day6
+	day7
 )
 
 set(BANAN_AOC2023_BIN   ${BANAN_BIN}/aoc2023)

userspace/aoc2023/day7/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(aoc2023_day7 CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(aoc2023_day7 ${SOURCES})
+target_compile_options(aoc2023_day7 PUBLIC -O2 -g)
+target_link_libraries(aoc2023_day7 PUBLIC libc ban)
+
+add_dependencies(aoc2023_day7 libc-install ban-install)
+
+add_custom_target(aoc2023_day7-install
+	COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/aoc2023_day7 ${BANAN_AOC2023_BIN}/day7
+	DEPENDS aoc2023_day7
+	DEPENDS aoc2023_always
+)
+
+add_dependencies(aoc2023 aoc2023_day7)
+add_dependencies(aoc2023-install aoc2023_day7-install)

userspace/aoc2023/day7/main.cpp

@@ -0,0 +1,167 @@
+#include <BAN/Vector.h>
+#include <BAN/String.h>
+
+#include <ctype.h>
+#include <stdio.h>
+#include <stdint.h>
+
+using i64 = int64_t;
+
+i64 parse_i64(BAN::StringView part)
+{
+	i64 result = 0;
+	for (char c : part)
+	{
+		if (!isdigit(c))
+			break;
+		result = (result * 10) + (c - '0');
+	}
+	return result;
+}
+
+struct Hand
+{
+	BAN::String hand;
+	i64 bid;
+};
+
+i64 card_score(char card, bool joker)
+{
+	if (card == 'A')
+		return 14;
+	if (card == 'K')
+		return 13;
+	if (card == 'Q')
+		return 12;
+	if (card == 'J')
+		return joker ? 1 : 11;
+	if (card == 'T')
+		return 10;
+
+	ASSERT('2' <= card && card <= '9');
+	return card - '0';
+}
+
+i64 hand_score_no_type(const Hand& hand, bool joker)
+{
+	ASSERT(hand.hand.size() == 5);
+	i64 score = 0;
+	for (char c : hand.hand)
+		score = (score << 4) | card_score(c, joker);
+	ASSERT(score < 1'000'000);
+	return score;
+}
+
+i64 hand_score(const Hand& hand, bool joker)
+{
+	ASSERT(hand.hand.size() == 5);
+
+	i64 joker_count = 0;
+	i64 cnt[26 + 10] {};
+	for (char c : hand.hand)
+	{
+		if (isdigit(c))
+			cnt[c - '0' +  0]++;
+		else if (c == 'J')
+			joker_count++;
+		else
+			cnt[c - 'A' + 10]++;
+	}
+
+	if (!joker)
+	{
+		cnt['J' - 'A' + 10] = joker_count;
+		joker_count = 0;
+	}
+	
+	for (size_t i = 0; i < 36; i++)
+		if (cnt[i] + joker_count >= 5)
+			return 6'000'000 + hand_score_no_type(hand, joker);
+	
+	for (size_t i = 0; i < 36; i++)
+		if (cnt[i] + joker_count >= 4)
+			return 5'000'000 + hand_score_no_type(hand, joker);
+	
+	for (size_t i = 0; i < 36; i++)
+		for (size_t j = 0; j < 36; j++)
+			if (i != j && cnt[i] + joker_count >= 3 && cnt[j] >= 2)
+				return 4'000'000 + hand_score_no_type(hand, joker);
+	
+	for (size_t i = 0; i < 36; i++)
+		if (cnt[i] + joker_count >= 3)
+			return 3'000'000 + hand_score_no_type(hand, joker);
+	
+	for (size_t i = 0; i < 36; i++)
+		for (size_t j = 0; j < 36; j++)
+			if (i != j && cnt[i] + joker_count >= 2 && cnt[j] >= 2)
+				return 2'000'000 + hand_score_no_type(hand, joker);
+	
+	for (size_t i = 0; i < 36; i++)
+		if (cnt[i] + joker_count >= 2)
+			return 1'000'000 + hand_score_no_type(hand, joker);
+	
+	return hand_score_no_type(hand, joker);
+}
+
+i64 puzzle(FILE* fp, bool joker)
+{
+	BAN::Vector<Hand> hands;
+
+	char buffer[128];
+	while (fgets(buffer, sizeof(buffer), fp))
+	{
+		BAN::StringView line(buffer);
+		if (line.size() < 7)
+			continue;
+
+		Hand hand;
+		hand.hand = line.substring(0, 5);
+		hand.bid = parse_i64(line.substring(6));
+		MUST(hands.push_back(hand));
+	}
+
+	// Very slow sorting algorithm
+	for (size_t i = 0; i < hands.size(); i++)
+	{
+		i64 l_score = hand_score(hands[i], joker);
+		for (size_t j = i + 1; j < hands.size(); j++)
+		{
+			i64 r_score = hand_score(hands[j], joker);
+			if (r_score > l_score)
+			{
+				Hand tmp = BAN::move(hands[i]);
+				hands[i] = BAN::move(hands[j]);
+				hands[j] = BAN::move(tmp);
+				l_score = r_score;
+			}
+		}
+	}
+
+	i64 score = 0;
+	for (size_t i = 0; i < hands.size(); i++)
+		score += (hands.size() - i) * hands[i].bid;
+	return score;
+}
+
+int main(int argc, char** argv)
+{
+	const char* file_path = "/usr/share/aoc2023/day7_input.txt";
+
+	if (argc >= 2)
+		file_path = argv[1];
+
+	FILE* fp = fopen(file_path, "r");
+	if (fp == nullptr)
+	{
+		perror("fopen");
+		return 1;
+	}
+
+	printf("puzzle1: %lld\n", puzzle(fp, false));
+
+	fseek(fp, 0, SEEK_SET);
+
+	printf("puzzle2: %lld\n", puzzle(fp, true));
+
+	fclose(fp);
+}