AOC-2024/12/main.go

package main

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

const FILE_PATH = "./input.txt"

//const FILE_PATH = "./sample.txt"

func LoadInput(filename string) ([]string, error) {
	file, err := os.Open(filename)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	var lines []string
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		lines = append(lines, scanner.Text())
	}

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

	return lines, nil
}

type structuredInput = [][]byte

func TransformInput(lines []string) structuredInput {
	var result = make([][]byte, 0)

	for _, line := range lines {
		result = append(result, []byte(line))
	}

	return result
}

func calcCircumAndSize(input structuredInput, visited [][]bool, char byte, x int, y int) (int, int) {
	visited[y][x] = true
	var size = 1
	var circum = 0
	var tempSize = 0
	var tempCircum = 0
	if x-1 < 0 || input[y][x-1] != char {
		circum += 1
	} else if !visited[y][x-1] {
		tempCircum, tempSize = calcCircumAndSize(input, visited, char, x-1, y)
		size += tempSize
		circum += tempCircum
	}

	if x+1 >= len(input[y]) || input[y][x+1] != char {
		circum += 1
	} else if !visited[y][x+1] {
		tempCircum, tempSize = calcCircumAndSize(input, visited, char, x+1, y)
		size += tempSize
		circum += tempCircum
	}

	if y-1 < 0 || input[y-1][x] != char {
		circum += 1
	} else if !visited[y-1][x] {
		tempCircum, tempSize = calcCircumAndSize(input, visited, char, x, y-1)
		size += tempSize
		circum += tempCircum
	}

	if y+1 >= len(input) || input[y+1][x] != char {
		circum += 1
	} else if !visited[y+1][x] {
		tempCircum, tempSize = calcCircumAndSize(input, visited, char, x, y+1)
		size += tempSize
		circum += tempCircum
	}

	return circum, size
}

type Fence struct {
	verL bool
	horU bool
	verR bool
	horD bool
}

func calcFenceAndSize(input structuredInput, visited [][]bool, char byte, x int, y int, fence [][]Fence) int {
	visited[y][x] = true
	var size = 1
	if x-1 < 0 || input[y][x-1] != char {
		fence[y+1][x-1+1].verL = true
	} else if !visited[y][x-1] {
		size += calcFenceAndSize(input, visited, char, x-1, y, fence)
	}

	if x+1 >= len(input[y]) || input[y][x+1] != char {
		fence[y+1][x+1+1].verR = true
	} else if !visited[y][x+1] {
		size += calcFenceAndSize(input, visited, char, x+1, y, fence)
	}

	if y-1 < 0 || input[y-1][x] != char {
		fence[y-1+1][x+1].horU = true
	} else if !visited[y-1][x] {
		size += calcFenceAndSize(input, visited, char, x, y-1, fence)
	}

	if y+1 >= len(input) || input[y+1][x] != char {
		fence[y+1+1][x+1].horD = true
	} else if !visited[y+1][x] {
		size += calcFenceAndSize(input, visited, char, x, y+1, fence)
	}

	return size
}

func Part1(input structuredInput) int {
	var result = 0

	var visited [][]bool = make([][]bool, len(input))
	var size int = 0
	var circum int = 0
	for i := 0; i < len(input); i++ {
		visited[i] = make([]bool, len(input[i]))
	}

	for y := 0; y < len(input); y++ {
		for x := 0; x < len(input[y]); x++ {
			if !visited[y][x] {
				circum, size = calcCircumAndSize(input, visited, input[y][x], x, y)
				result += circum * size
			}
		}
	}

	return result
}

func Part2(input structuredInput) int {
	var result = 0

	var visited [][]bool = make([][]bool, len(input))
	var size int = 0
	var fence [][]Fence
	var sides int
	var insideSide1 bool
	var insideSide2 bool
	for i := 0; i < len(input); i++ {
		visited[i] = make([]bool, len(input[i]))

	}

	for y := 0; y < len(input); y++ {
		for x := 0; x < len(input[y]); x++ {
			if !visited[y][x] {
				fence = make([][]Fence, len(input)+2)
				for i := 0; i < len(input)+2; i++ {
					fence[i] = make([]Fence, len(input[0])+2)
				}
				size = calcFenceAndSize(input, visited, input[y][x], x, y, fence)
				sides = 0
				for m := 0; m < len(fence); m++ {
					insideSide1 = false
					insideSide2 = false
					for n := 0; n < len(fence[m]); n++ {
						if insideSide1 && !fence[m][n].horU {
							insideSide1 = false
							sides += 1
						} else if !insideSide1 && fence[m][n].horU {
							insideSide1 = true
						}
						if insideSide2 && !fence[m][n].horD {
							insideSide2 = false
							sides += 1
						} else if !insideSide2 && fence[m][n].horD {
							insideSide2 = true
						}
					}
					if insideSide1 {
						sides += 1
					}
					if insideSide2 {
						sides += 1
					}
				}

				for n := 0; n < len(fence[0]); n++ {
					insideSide1 = false
					insideSide2 = false
					for m := 0; m < len(fence); m++ {
						if insideSide1 && !fence[m][n].verL {
							insideSide1 = false
							sides += 1
						} else if !insideSide1 && fence[m][n].verL {
							insideSide1 = true
						}
						if insideSide2 && !fence[m][n].verR {
							insideSide2 = false
							sides += 1
						} else if !insideSide2 && fence[m][n].verR {
							insideSide2 = true
						}
					}
					if insideSide1 {
						sides += 1
					}
					if insideSide2 {
						sides += 1
					}
				}
				result += size * sides
			}
		}
	}

	return result
}

func main() {
	var start time.Time
	var elapsed time.Duration = 0
	input, err := LoadInput(FILE_PATH)
	if err != nil {
		fmt.Println("Error loading input:", err)
		return
	}

	structuredInput := TransformInput(input)
	fmt.Println("Structured Input:", structuredInput)

	start = time.Now()
	fmt.Println("Solution Part 1: ", Part1(structuredInput))
	elapsed = time.Since(start)
	fmt.Printf("Part 1 took %s\n", elapsed)

	start = time.Now()
	fmt.Println("Solution Part 2: ", Part2(structuredInput))
	elapsed = time.Since(start)
	fmt.Printf("Part 2 took %s\n", elapsed)
}