AdventOfCode2021/18/main.go

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"time"
)

func mustAtoi(line rune) int {
	i, _ := strconv.Atoi(string(line))
	return i
}

func main() {
	start := time.Now()
	partOne()
	duration := time.Since(start)
	partTwo()
	duration2 := time.Since(start)
	fmt.Printf("p1: %s, p2: %s\n", duration, duration2-duration)
}

func makeScanner(test bool) *bufio.Scanner {
	var f *os.File
	if test {
		f, _ = os.Open("inputs/testinput")
	} else {
		f, _ = os.Open("inputs/input")
	}
	reader := bufio.NewReader(f)
	return bufio.NewScanner(reader)
}

type pair struct {
	parent *pair
	leftp  *pair
	left   int
	rightp *pair
	right  int
}

func Parse(raw string) *pair {
	root := &pair{}
	var current *pair
	left := true
	for _, v := range raw {
		switch v {
		case '[':
			if current == nil {
				current = root
			} else {
				p := &pair{parent: current}
				if left {
					current.leftp = p
				} else {
					current.rightp = p
				}
				current = p
			}
			left = true
		case ']':
			current = current.parent
		case ',':
			left = false
		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
			if left {
				current.left = mustAtoi(v)
			} else {
				current.right = mustAtoi(v)
			}
		case ' ':
			continue
		default:
			panic("what the: " + string(v))
		}
	}
	return root
}

func (p *pair) String() string {
	var left, right string
	if p.leftp == nil {
		left = fmt.Sprintf("%d", p.left)
	} else {
		left = p.leftp.String()
	}
	if p.rightp == nil {
		right = fmt.Sprintf("%d", p.right)
	} else {
		right = p.rightp.String()
	}
	return fmt.Sprintf("[%s,%s]", left, right)
}

func (p *pair) Magnitude() int {
	left := 0
	right := 0
	if p.leftp == nil {
		left = p.left
	} else {
		left = p.leftp.Magnitude()
	}
	if p.rightp == nil {
		right = p.right
	} else {
		right = p.rightp.Magnitude()
	}
	return left*3 + right*2
}

func Add(left, right *pair) *pair {
	return &pair{
		leftp:  left,
		rightp: right,
	}
}

func Reduce(p *pair) *pair {
	return &pair{} // ???
}

func Split(p *pair) *pair {
	if p.left > 9 {
		p.leftp = &pair{
			left:  p.left / 2,
			right: (p.left / 2) + (p.left % 2),
		}
		p.left = 0
		return p
	}
	if p.right > 9 {
		p.rightp = &pair{
			left:  p.right / 2,
			right: (p.right / 2) + (p.right % 2),
		}
		p.right = 0
		return p
	}
	return p
}

func MustExplode(depth int, p *pair) bool {
	if depth >= 4 {
		return true
	}
	if p.leftp != nil {
		m := MustExplode(depth+1, p.leftp)
		if m {
			return true
		}
	}
	if p.rightp != nil {
		m := MustExplode(depth+1, p.rightp)
		if m {
			return true
		}
	}
	return false
}

func partOne() {
	scanner := makeScanner(false)

	scanner.Scan()
	line := scanner.Text()
	total := Parse(line)
	for scanner.Scan() {
		line := scanner.Text()
		total = Add(total, Parse(line))
	}
	fmt.Println(total)
}

func partTwo() {
	scanner := makeScanner(false)

	for scanner.Scan() {
		// line := scanner.Text()
	}
}