adventofcode-2023/day_04/solution_04a.nim

import std/[cmdline, math, sequtils, setutils, strformat, strscans, strutils]

var result = 0
var fn = if paramCount() > 0: paramStr(1) else: "input_04.txt"
var lines = readFile(fn).strip.splitLines

# ASSUMPTION: lottery numbers are < 128
type
    Card = ref object
        play, pot: set[int8]
var cards: seq[Card]

proc points(card: Card): int =
    let matches = (card.play * card.pot).len
    if matches == 1:
        result = 1
    elif matches > 1:
        result = 2 ^ (matches - 1)
    else:
        result = 0


for line in lines:
    var cardno: int
    let cardspec = line.split(":", 1)

    if scanf(cardspec[0].strip, "Card$s$i", cardno):
        let card = new Card
        card.play = cardspec[1].split("|")[0].strip.splitWhitespace().mapIt(it.strip).mapIt(it.parseInt).mapIt(it.int8).toSet
        card.pot = cardspec[1].split("|")[1].strip.splitWhitespace().mapIt(it.strip).mapIt(it.parseInt).mapIt(it.int8).toSet
        echo &"Card {cardno}: {card.play}, {card.pot} => {card.points}"
        cards.add(card)
        result += card.points

echo &"Cards processed: {cards.len}"
echo &"Result: {result}"

case fn:
    of "input_04.txt":
        assert result == 18519
    of "sample_input_04.txt":
        assert result == 13