Found a C per-char solution, that is, no lines, splitting, lookahead, etc. It wasn’t even necessary to keep match lengths for the color names because they all have unique characters, e.g. ‘b’ only occurs in “blue” so then you can attribute the count to that color.

int main()
{
	int p1=0,p2=0, id=1,num=0, r=0,g=0,b=0, c;

	while ((c = getchar()) != EOF)
		if (c==',' || c==';' || c==':') num = 0; else
		if (c>='0' && c<='9') num = num*10 + c-'0'; else
		if (c=='d') r = MAX(r, num); else
		if (c=='g') g = MAX(g, num); else
		if (c=='b') b = MAX(b, num); else
		if (c=='\n') {
			p1 += (r<=12 && g<=13 && b<=14) * id;
			p2 += r*g*b;
			r=g=b=0; id++;
		}

	printf("%d %d\n", p1, p2);
	return 0;
}

Golfed:

c,p,P,i,n,r,g,b;main(){while(~
(c=getchar()))c==44|c==58|59==
c?n=0:c>47&c<58?n=n*10+c-48:98
==c?b=b>n?b:n:c=='d'?r=r>n?r:n
:c=='g'?g=g>n?g:n:10==c?p+=++i
*(r<13&g<14&b<15),P+=r*g*b,r=g
=b=0:0;printf("%d %d\n",p,P);}

Rust

Pretty straightforward this time, the bulk of the work was clearly in parsing the input.

Not too tricky today. Part 2 wasn’t as big of a curveball as yesterday thankfully. I don’t think it’s the cleanest code I’ve ever written, but hey - the whole point of this is to get better at Rust, so I’ll definitely be learning as I go, and coming back at the end to clean a lot of these up. I think for this one I’d like to look into a parsing crate like nom to clean up all the spliting and unwrapping in the two from() methods.

https://github.com/capitalpb/advent_of_code_2023/blob/main/src/solvers/day02.rs

#[derive(Debug)]
struct Hand {
    blue: usize,
    green: usize,
    red: usize,
}

impl Hand {
    fn from(input: &str) -> Hand {
        let mut hand = Hand {
            blue: 0,
            green: 0,
            red: 0,
        };

        for color in input.split(", ") {
            let color = color.split_once(' ').unwrap();
            match color.1 {
                "blue" => hand.blue = color.0.parse::().unwrap(),
                "green" => hand.green = color.0.parse::().unwrap(),
                "red" => hand.red = color.0.parse::().unwrap(),
                _ => unreachable!("malformed input"),
            }
        }

        hand
    }
}

#[derive(Debug)]
struct Game {
    id: usize,
    hands: Vec,
}

impl Game {
    fn from(input: &str) -> Game {
        let (id, hands) = input.split_once(": ").unwrap();
        let id = id.split_once(" ").unwrap().1.parse::().unwrap();
        let hands = hands.split("; ").map(Hand::from).collect();
        Game { id, hands }
    }
}

pub struct Day02;

impl Solver for Day02 {
    fn star_one(&self, input: &str) -> String {
        input
            .lines()
            .map(Game::from)
            .filter(|game| {
                game.hands
                    .iter()
                    .all(|hand| hand.blue <= 14 && hand.green <= 13 && hand.red <= 12)
            })
            .map(|game| game.id)
            .sum::()
            .to_string()
    }

    fn star_two(&self, input: &str) -> String {
        input
            .lines()
            .map(Game::from)
            .map(|game| {
                let max_blue = game.hands.iter().map(|hand| hand.blue).max().unwrap();
                let max_green = game.hands.iter().map(|hand| hand.green).max().unwrap();
                let max_red = game.hands.iter().map(|hand| hand.red).max().unwrap();

                max_blue * max_green * max_red
            })
            .sum::()
            .to_string()
    }
}

I had some time, so here’s a terrible solution in Uiua (Run it here) :

Lim ← [14 13 12]
{"Game 1: 3 blue, 4 red; 1 red, 2 green, 6 blue; 2 green"
 "Game 2: 1 blue, 2 green; 3 green, 4 blue, 1 red; 1 green, 1 blue"
 "Game 3: 8 green, 6 blue, 20 red; 5 blue, 4 red, 13 green; 5 green, 1 red"
 "Game 4: 1 green, 3 red, 6 blue; 3 green, 6 red; 3 green, 15 blue, 14 red"
 "Game 5: 6 red, 1 blue, 3 green; 2 blue, 1 red, 2 green"}

LtoDec ← ∧(+ ×10:) :0
StoDec ← LtoDec▽≥0. ▽≤9. -@0
FilterMax! ← /↥≡(StoDec⊢↙ ¯1)⊔⊏⊚≡(/×^1⊢).⊔
# Build 'map' of draws for each game
∵(□≡(∵(⬚@\s↙2 ⊔) ⇌) ↯¯1_2 ↘ 2⊜□≠@\s . ⊔)
# Only need the max for each colour
≡(⊂⊂⊃⊃(FilterMax!(="bl")) (FilterMax!(="gr")) (FilterMax!(="re")))
# part 1 - Compare against limits, and sum game numbers
/+▽:+1⇡⧻. ≡(/×≤0-Lim).
# part 2 - Multiply the maxes in each game and then sum.
/+/×⍉:

Factor on github (with comments and imports):

: known-color ( color-phrases regexp -- n )
  all-matching-subseqs [ 0 ] [
    [ split-words first string>number ] map-supremum
  ] if-empty
;

: line>known-rgb ( str -- game-id known-rgb )
  ": " split1 [ split-words last string>number ] dip
  R/ \d+ red/ R/ \d+ green/ R/ \d+ blue/
  [ known-color ] tri-curry@ tri 3array
;

: possible? ( known-rgb test-rgb -- ? )
  v<= [ ] all?
;

: part1 ( -- )
  "vocab:aoc-2023/day02/input.txt" utf8 file-lines
  [ line>known-rgb 2array ]
  [ last { 12 13 14 } possible? ] map-filter
  [ first ] map-sum .
;

: part2 ( -- )
  "vocab:aoc-2023/day02/input.txt" utf8 file-lines
  [ line>known-rgb nip product ] map-sum .
;

This was mostly straightforward… basically just parsing input. Here are my condensed solutions in Python

Game = dict[str, int]

RED_MAX   = 12
GREEN_MAX = 13
BLUE_MAX  = 14

def read_game(stream=sys.stdin) -> Game:
    try:
        game_string, cubes_string = stream.readline().split(':')
    except ValueError:
        return {}

    game: Game = defaultdict(int)
    game['id'] = int(game_string.split()[-1])

    for cubes in cubes_string.split(';'):
        for cube in cubes.split(','):
            count, color = cube.split()
            game[color] = max(game[color], int(count))

    return game

def read_games(stream=sys.stdin) -> Iterator[Game]:
    while game := read_game(stream):
        yield game

def is_valid_game(game: Game) -> bool:
    return all([
        game['red']   <= RED_MAX,
        game['green'] <= GREEN_MAX,
        game['blue']  <= BLUE_MAX,
    ])

def main(stream=sys.stdin) -> None:
    valid_games = filter(is_valid_game, read_games(stream))
    sum_of_ids  = sum(game['id'] for game in valid_games)
    print(sum_of_ids)

def power(game: Game) -> int:
    return game['red'] * game['green'] * game['blue']

def main(stream=sys.stdin) -> None:
    sum_of_sets = sum(power(game) for game in read_games(stream))
    print(sum_of_sets)

GitHub Repo

Today in Zig

Spent most of the time running down annoying typos in the tokenizer.

Was pretty simple in Python with a regex to get the game number, and then the count of color. for part 2 instead of returning true/false whether the game is valid, you just max the count per color. No traps like in the first one, that I’ve seen, so it was surprisingly easy

def process_game(line: str):
    game_id = int(re.findall(r'game (\d+)*', line)[0])

    colon_idx = line.index(":")
    draws = line[colon_idx+1:].split(";")
    # print(draws)
    
    if is_game_valid(draws):
        # print("Game %d is possible"%game_id)
        return game_id
    return 0

            
def is_game_valid(draws: list):
    for draw in draws:
        red = get_nr_of_in_draw(draw, 'red')
        if red > MAX_RED:
            return False
        
        green = get_nr_of_in_draw(draw, 'green')
        if green > MAX_GREEN:
            return False
        
        blue = get_nr_of_in_draw(draw, 'blue')
        if blue > MAX_BLUE:
            return False    
    return True
        
            
def get_nr_of_in_draw(draw: str, color: str):
    if color in draw:
        nr = re.findall(r'(\d+) '+color, draw)
        return int(nr[0])
    return 0


# f = open("input.txt", "r")
f = open("input_real.txt", "r")
lines = f.readlines()
sum = 0
for line in lines:
    sum += process_game(line.strip().lower())
print("Answer: %d"%sum)

My solutions in C: https://git.sr.ht/~aidenisik/aoc23/tree/master/item/day2

Most of this is just reading the data, surely there’s a better way to do this lol.

Dart solution

Quite straightforward, though there’s a sneaky trap in the test data for those of us who don’t read the rules carefully enough.

Read, run and edit this solution in your browser: https://dartpad.dev/?id=203b3f0a9a1ad7a51daf14a1aeb6cf67

parseLine(String s) {
  var game = s.split(': ');
  var num = int.parse(game.first.split(' ').last);
  var rounds = game.last.split('; ');
  var cubes = [
    for (var (e) in rounds)
      {
        for (var ee in e.split(', '))
          ee.split(' ').last: int.parse(ee.split(' ').first)
      }
  ];
  return MapEntry(num, cubes);
}

/// collects the max of the counts from both maps.
Map merge2(Map a, Map b) => {
      for (var k in {...a.keys, ...b.keys}) k: max(a[k] ?? 0, b[k] ?? 0)
    };

var limit = {"red": 12, "green": 13, "blue": 14};

bool isGood(Map test) =>
    limit.entries.every((e) => (test[e.key] ?? 0) <= e.value);

part1(List lines) => lines
    .map(parseLine)
    .where((e) => e.value.every(isGood))
    .map((e) => e.key)
    .sum;

part2(List lines) => lines
    .map(parseLine)
    .map((e) => e.value.reduce(merge2))
    .map((e) => e.values.reduce((s, t) => s * t))
    .sum;

Getting my head around parsing tricks for python, maybe abusing dicts as a replacement for a types, but appears to be working: https://gist.github.com/purplemonkeymad/983eec7ff0629e8834163b17ec673958

Mostly an input parsing problem this time, but it was fun to use Hares tokenizer functions:

-- SPDX-FileCopyrightText: 2023 Jummit
--
-- SPDX-License-Identifier: GPL-3.0-or-later

local colors = {"blue", "red", "green"}
local available = {red = 12, blue = 14, green = 13}
local possible = 0
local id = 0
local min = 0

for game in io.open("2.input"):lines() do
  id = id + 1
  game = game:gsub("Game %d+: ", "").."; "
  local max = {red = 0, blue = 0, green = 0}
  for show in game:gmatch(".-; ") do
    for _, color in ipairs(colors) do
      local num = tonumber(show:match("(%d+) "..color))
      if num then
        max[color] = math.max(max[color], num)
      end
    end
  end
  min = min + max.red * max.blue * max.green
  local thisPossible = true
  for _, color in ipairs(colors) do
    if max[color] > available[color] then
      thisPossible = false
      break
    end
  end
  if thisPossible then
    possible = possible + id
  end
end

print(possible)
print(min)

// SPDX-FileCopyrightText: 2023 Jummit
//
// SPDX-License-Identifier: GPL-3.0-or-later

use strconv;
use types;
use strings;
use io;
use bufio;
use os;
use fmt;

const available: []uint = [12, 13, 14];

fn color_id(color: str) const uint = {
	switch (color) {
	case "red" => return 0;
	case "green" => return 1;
	case "blue" => return 2;
	case => abort();
	};
};

export fn main() void = {
	const file = os::open("2.input")!;
	defer io::close(file)!;
	const scan = bufio::newscanner(file, types::SIZE_MAX);
	let possible: uint = 0;
	let min: uint = 0;

	for (let id = 1u; true; id += 1) {
		const line = match(bufio::scan_line(&scan)!) {
		case io::EOF =>
			break;
		case let line: const str =>
			yield strings::sub(
					line,
					strings::index(line, ": ") as size + 2,
					strings::end);
		};
		let max: []uint = [0, 0, 0];
		let tok = strings::rtokenize(line, "; ");
		for (true) {
			const show = match(strings::next_token(&tok)) {
			case void =>
				break;
			case let show: str =>
				yield show;
			};
			const pairs = strings::tokenize(show, ", ");
			for (true) {
				const pair: (str, str) = match(strings::next_token(&pairs)) {
				case void =>
					break;
				case let pair: str =>
					let tok = strings::tokenize(pair, " ");
					yield (
						strings::next_token(&tok) as str,
						strings::next_token(&tok) as str
					);
				};
				let color = color_id(pair.1);
				let amount = strconv::stou(pair.0)!;
				if (amount > max[color]) max[color] = amount;
			};
		};
		if (max[0] <= available[0] && max[1] <= available[1] && max[2] <= available[2]) {
			fmt::printfln("{}", id)!;
			possible += id;
		};
		min += max[0] * max[1] * max[2];
	};
	
	fmt::printfln("{}", possible)!;
	fmt::printfln("{}", min)!;
};

Did mine in Odin. Found this day’s to be super easy, most of the challenge was just parsing.

package day2

import "core:fmt"
import "core:strings"
import "core:strconv"
import "core:unicode"

Round :: struct {
    red: int,
    green: int,
    blue: int,
}

parse_round :: proc(s: string) -> Round {
    ret: Round

    rest := s
    for {
        nextNumAt := strings.index_proc(rest, unicode.is_digit)
        if nextNumAt == -1 do break
        rest = rest[nextNumAt:]

        numlen: int
        num, ok := strconv.parse_int(rest, 10, &numlen)
        rest = rest[numlen+len(" "):]

        if rest[:3] == "red" {
            ret.red = num
        } else if rest[:4] == "blue" {
            ret.blue = num
        } else if rest[:5] == "green" {
            ret.green = num
        }
    }

    return ret
}

Game :: struct {
    id: int,
    rounds: [dynamic]Round,
}

parse_game :: proc(s: string) -> Game {
    ret: Game

    rest := s[len("Game "):]

    idOk: bool
    idLen: int
    ret.id, idOk = strconv.parse_int(rest, 10, &idLen)
    rest = rest[idLen+len(": "):]

    for len(rest) > 0 {
        endOfRound := strings.index_rune(rest, ';')
        if endOfRound == -1 do endOfRound = len(rest)

        append(&ret.rounds, parse_round(rest[:endOfRound]))
        rest = rest[min(endOfRound+1, len(rest)):]
    }

    return ret
}

is_game_possible :: proc(game: Game) -> bool {
    for round in game.rounds {
        if round.red   > 12 ||
           round.green > 13 ||
           round.blue  > 14 {
            return false
        }
    }
    return true
}

p1 :: proc(input: []string) {
    totalIds := 0

    for line in input {
        game := parse_game(line)
        defer delete(game.rounds)

        if is_game_possible(game) do totalIds += game.id
    }

    fmt.println(totalIds)
}

p2 :: proc(input: []string) {
    totalPower := 0

    for line in input {
        game := parse_game(line)
        defer delete(game.rounds)

        minRed   := 0
        minGreen := 0
        minBlue  := 0
        for round in game.rounds {
            minRed   = max(minRed  , round.red  )
            minGreen = max(minGreen, round.green)
            minBlue  = max(minBlue , round.blue )
        }

        totalPower += minRed * minGreen * minBlue
    }

    fmt.println(totalPower)
}

C# - a tad bit overkill for this. I was worried that we’d need more statistical analysis in part 2, so I designed my solution around that. I ended up cutting everything back when Max() was enough for both parts.

https://github.com/warriordog/advent-of-code-2023/tree/main/Solutions/Day02

My (awful) Python solves. Much easier than day 1’s, although I did run into an issue with trimming whitespace characters with my approach (Game 96 wouldn’t flag properly).

with open('02A_input.txt', 'r') as file:
    data = file.readlines()
    
possibleGames=[]

for game in data:
    # Find Game number
    game = game.removeprefix("Game ")
    gameNumber = int(game[0:game.find(":")])
    # Break Game into rounds (split using semicolons)
    game=game[game.find(":")+1:]
    rounds=game.split(";")
    # For each round, determine the maximum number of Red, Blue, Green items shown at a time
    rgb=[0,0,0]
    for round in rounds:
        combos=round.split(",")
        for combo in combos:
            combo=combo.strip()
            number=int(combo[0:combo.find(" ")])
            if combo.endswith("red"):
                if number>rgb[0]:
                    rgb[0]=number
            elif combo.endswith("green"):
                if number>rgb[1]:
                    rgb[1]=number
            elif combo.endswith("blue"):
                if number>rgb[2]:
                    rgb[2]=number
    # If Red>12, Green>13, Blue>14, append Game number to possibleGames
    if not (rgb[0]>12 or rgb[1]>13 or rgb[2]>14):
        possibleGames.append(gameNumber)

print(sum(possibleGames))

with open('02A_input.txt', 'r') as file:
    data = file.readlines()
    
powers=[]

for game in data:
    # Find Game number
    game = game.removeprefix("Game ")
    # Break Game into rounds (split using semicolons)
    game=game[game.find(":")+1:]
    rounds=game.split(";")
    # For each round, determine the maximum number of Red, Blue, Green items shown at a time
    # Note: This could be faster, since we don't need to worry about actual rounds
    rgb=[0,0,0]
    for round in rounds:
        combos=round.split(",")
        for combo in combos:
            combo=combo.strip()
            number=int(combo[0:combo.find(" ")])
            if combo.endswith("red"):
                if number>rgb[0]:
                    rgb[0]=number
            elif combo.endswith("green"):
                if number>rgb[1]:
                    rgb[1]=number
            elif combo.endswith("blue"):
                if number>rgb[2]:
                    rgb[2]=number
    # Multiple R, G, B to find the "power" of the game
    # Append Power to the list
    powers.append(rgb[0]*rgb[1]*rgb[2])
    
print(sum(powers))