• 12 Posts
  • 44 Comments
Joined 9 months ago
Cake day: September 17th, 2023
  • reboot6675@sopuli.xyzOPtoPrivacy@lemmy.ml•Got annoyed by my gym
    2·
    2 months ago

    This would be the best way. Unfortunately they made it the other way around. A screen at the door shows the code, and you scan it with the app.

    In my previous gym the code was on the app, but I’m not sure anymore if it was static or it changed over time. But the reader on the door was awful, I used to spend a good 3 minutes trying different angles with my phone to make it recognize the code.

  • reboot6675@sopuli.xyztoAdvent Of Code@programming.dev•🦌 - 2023 DAY 16 SOLUTIONS -🦌
    1·
    6 months ago

    Golang

    Avoided recursion by having an array of “pending paths”. Whenever I hit a splitter, I follow one of the paths straight away, and push the starting point and direction of the other path to the array.

    First time I ran it, hit an infinite loop. Handled it by skipping “|” and “-” if they have been visited already.

    Part 2 is the same code as part 1 but I just check all the possible starting points.

    Code 
    package main

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

type Direction int

const (
	UP    Direction = 0
	DOWN  Direction = 1
	LEFT  Direction = 2
	RIGHT Direction = 3
)

type LightPoint struct {
	row int
	col int
	dir Direction
}

func solve(A [][]rune, start LightPoint) int {
	m := len(A)
	n := len(A[0])
	visited := make([]bool, m*n)
	points := []LightPoint{}
	points = append(points, start)

	for len(points) > 0 {
		current := points[0]
		points = points[1:]
		i := current.row
		j := current.col
		dir := current.dir

		for {
			if i < 0 || i >= m || j < 0 || j >= n {
				break
			}
			if visited[i*n+j] && (A[i][j] == '-' || A[i][j] == '|') {
				break
			}

			visited[i*n+j] = true

			if A[i][j] == '.' ||
				(A[i][j] == '-' && (dir == LEFT || dir == RIGHT)) ||
				(A[i][j] == '|' && (dir == UP || dir == DOWN)) {
				switch dir {
				case UP:
					i--
				case DOWN:
					i++
				case LEFT:
					j--
				case RIGHT:
					j++
				}
				continue
			}

			if A[i][j] == '\\' {
				switch dir {
				case UP:
					dir = LEFT
					j--
				case DOWN:
					dir = RIGHT
					j++
				case LEFT:
					dir = UP
					i--
				case RIGHT:
					dir = DOWN
					i++
				}
				continue
			}

			if A[i][j] == '/' {
				switch dir {
				case UP:
					dir = RIGHT
					j++
				case DOWN:
					dir = LEFT
					j--
				case LEFT:
					dir = DOWN
					i++
				case RIGHT:
					dir = UP
					i--
				}
				continue
			}

			if A[i][j] == '-' && (dir == UP || dir == DOWN) {
				points = append(points, LightPoint{row: i, col: j + 1, dir: RIGHT})
				dir = LEFT
				j--
				continue
			}

			if A[i][j] == '|' && (dir == LEFT || dir == RIGHT) {
				points = append(points, LightPoint{row: i + 1, col: j, dir: DOWN})
				dir = UP
				i--
			}
		}
	}

	energized := 0
	for _, v := range visited {
		if v {
			energized++
		}
	}
	return energized
}

func part1(A [][]rune) {
	start := LightPoint{row: 0, col: 0, dir: RIGHT}
	energized := solve(A, start)
	fmt.Println(energized)
}

func part2(A [][]rune) {
	m := len(A)
	n := len(A[0])
	max := -1

	for i := 0; i < m; i++ {
		start := LightPoint{row: i, col: 0, dir: RIGHT}
		energized := solve(A, start)
		if energized > max {
			max = energized
		}
		start = LightPoint{row: 0, col: n - 1, dir: LEFT}
		energized = solve(A, start)
		if energized > max {
			max = energized
		}
	}

	for j := 0; j < n; j++ {
		start := LightPoint{row: 0, col: j, dir: DOWN}
		energized := solve(A, start)
		if energized > max {
			max = energized
		}
		start = LightPoint{row: m - 1, col: j, dir: UP}
		energized = solve(A, start)
		if energized > max {
			max = energized
		}
	}

	fmt.Println(max)
}

func main() {
	// file, _ := os.Open("sample.txt")
	file, _ := os.Open("input.txt")
	defer file.Close()

	scanner := bufio.NewScanner(file)

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

	var A [][]rune
	for _, line := range lines {
		A = append(A, []rune(line))
	}

	// part1(A)
	part2(A)
}