AOC2022/day13/day13.go

package main

import (
	"AOC2022/helper"
	"fmt"
	"strconv"
)

func main() {
	//args := os.Args[1:]
	lines := helper.ReadTextFile("day13/input")
	result := 0
	index := 1
	for i := 0; i < len(lines); i += 3 {
		fmt.Println(lines[i])
		fmt.Println(lines[i+1])
		fmt.Println(comparePair(lines[i], lines[i+1]))
		fmt.Println()
		if comparePair(lines[i], lines[i+1]) == 0 {
			result += index
		}

		index++
	}
	fmt.Println(result)

}

// 0 Right Order
//-1 Left Value to high
//-2 Right had no values left
func comparePair(left string, right string) int {
	lefIndex := 0
	rightIndex := 0
	currentElemLeft := 0
	currentElemRight := 0
	leftElementType := 0
	rightElementType := 0
	for lefIndex < len(left)-1 {
		lefIndex, leftElementType = getNextElement(left, lefIndex)
		rightIndex, rightElementType = getNextElement(right, rightIndex)
		if leftElementType == -1 {
			return 0
		}
		if leftElementType == -2 {
			for rightElementType != -2 && rightElementType != 0 {
				rightIndex, rightElementType = getNextElement(right, rightIndex)
				if rightElementType == -1 {
					return -2
				}
			}
			if rightElementType == 0 {
				for leftElementType != 0 {
					lefIndex, leftElementType = getNextElement(left, lefIndex)
					if leftElementType == -1 || leftElementType == -3 {
						return -2
					}
				}
			}
		}
		if leftElementType == -3 {
			rightIndex = getEndofCurrentArray(right, rightIndex)
			rightElementType = -3
		}
		if leftElementType == 0 {
			for rightElementType != 0 {
				rightIndex, rightElementType = getNextElement(right, rightIndex)
				if rightElementType == -1 || rightElementType == -3 {
					return -2
				}
			}
			currentElemLeft, lefIndex = readElement(left, lefIndex)
			currentElemRight, rightIndex = readElement(right, rightIndex)
			if currentElemLeft > currentElemRight {
				return -1
			}
			if currentElemLeft < currentElemRight {
				return 0
			}
		}
	}
	return 0
}

// 0 Element
//-1 End Packet
//-2 Start Array
//-3 End Array
//-4 Seperator
func getNextElement(packet string, currentIndex int) (int, int) {
	index := currentIndex + 1
	for index < len(packet) {
		switch packet[index] {
		case ',':
			index++
			break
		case '[':
			return index, -2
			break
		case ']':
			if index < len(packet)-1 {
				return index, -3
			} else {
				index++
			}
			break
		default:
			return index, 0
		}
	}
	return index, -1
}

func getEndofCurrentArray(packet string, currentIndex int) int {
	index := currentIndex
	openedArrays := 1
	for openedArrays > 0 && index < len(packet) {
		switch packet[index] {
		case ']':
			openedArrays--
		case '[':
			openedArrays++
		}
		index++
	}
	if openedArrays == 0 {
		return index
	} else {
		return -1
	}
}

func readElement(packet string, currentIndex int) (element, newIndex int) {
	index := currentIndex
	newIndex = 0
	for newIndex == 0 {
		switch packet[index] {
		case ',':
			newIndex = index
			break
		case ']':
			newIndex = index
			break
		default:
			index++
		}
	}
	return helper.RemoveError(strconv.Atoi(packet[currentIndex:newIndex])), newIndex - 1
}