aoc2024/day-24/internal/one/util.go

package one

import (
	"bufio"
	"io"
	"strconv"
	"strings"
)

const (
	left = iota * 2
	right
	target
)

func parseLines(r io.Reader) (map[string]int, []expression, error) {
	initial := make(map[string]int)
	wires := make(map[string]int)
	expressions := []expression{}

	var inGates bool
	scanner := bufio.NewScanner(r)
	for scanner.Scan() {
		line := scanner.Text()

		if line == "" {
			inGates = true
			continue
		}

		if inGates {
			parts := strings.Split(line, " ")

			wires[parts[left]] = noValue
			wires[parts[right]] = noValue
			wires[parts[target]] = noValue

			var op rune
			switch parts[1] {
			case "AND":
				op = AND
			case "OR":
				op = OR
			case "XOR":
				op = XOR
			}
			expressions = append(expressions, newExpression(parts[left], parts[right], parts[target], op))
		} else {
			parts := strings.Split(line, ": ")
			initial[parts[0]] = mustConv(parts[1])
		}
	}

	if err := scanner.Err(); err != nil {
		return nil, nil, err
	}

	for k, v := range initial {
		wires[k] = v
	}

	return wires, expressions, nil
}

func mustConv(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		panic(err)
	}
	return n
}

func anyNegative(wires map[string]int) bool {
	for _, v := range wires {
		if v == -1 {
			return true
		}
	}
	return false
}

func filter(wires map[string]int, fn func(string) bool) []zWire {
	var filtered []zWire
	for name, value := range wires {
		if fn(name) {
			filtered = append(filtered, zWire{name, value})
		}
	}
	return filtered
}