day6.go

package main

import (
	"bufio"
	"fmt"
	"os"
	//	"regexp"
	"strconv"
	"strings"
)

// Because your neighbors keep defeating you in the holiday house decorating
// contest year after year, you've decided to deploy one million lights in a
// 1000x1000 grid.
//
// Furthermore, because you've been especially nice this year, Santa has mailed
// you instructions on how to display the ideal lighting configuration.
//
// Lights in your grid are numbered from 0 to 999 in each direction; the lights
// at each corner are at 0,0, 0,999, 999,999, and 999,0. The instructions
// include whether to turn on, turn off, or toggle various inclusive ranges
// given as coordinate pairs. Each coordinate pair represents opposite corners
// of a rectangle, inclusive; a coordinate pair like 0,0 through 2,2 therefore
// refers to 9 lights in a 3x3 square. The lights all start turned off.
//
// To defeat your neighbors this year, all you have to do is set up your lights
// by doing the instructions Santa sent you in order.
//
// For example:
//
//   - turn on 0,0 through 999,999 would turn on (or leave on) every light.
//   - toggle 0,0 through 999,0 would toggle the first line of 1000 lights,
//     turning off the ones that were on, and turning on the ones that were
//     off.
//   - turn off 499,499 through 500,500 would turn off (or leave off) the
//     middle four lights.
//
// After following the instructions, how many lights are lit?

// --- Part Two ---
//
// You just finish implementing your winning light pattern when you realize
// you mistranslated Santa's message from Ancient Nordic Elvish.
//
// The light grid you bought actually has individual brightness controls; each
// light can have a brightness of zero or more. The lights all start at zero.
//
// The phrase turn on actually means that you should increase the brightness
// of those lights by 1.
//
// The phrase turn off actually means that you should decrease the brightness
// of those lights by 1, to a minimum of zero.
//
// The phrase toggle actually means that you should increase the brightness of
// those lights by 2.
//
// What is the total brightness of all lights combined after following Santa's
// instructions?
//
// For example:
//
//  - turn on 0,0 through 0,0 would increase the total brightness by 1.
//  - toggle 0,0 through 999,999 would increase the total brightness by
//    2000000.

func main() {
	file, err := os.Open("./day6input.txt")
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	}

	defer file.Close()

	fmt.Println("--- Day 6: Probably a Fire Hazard ---")

	lights := [1000][1000]bool{}
	lights_p2 := [1000][1000]int{}

	scanner := bufio.NewScanner(file)
	x_start := 0
	y_start := 0
	x_end := 0
	y_end := 0

	// Main Loop
	for scanner.Scan() {
		line := scanner.Text()
		fmt.Printf("%q ", line)

		splitline := strings.Split(line, " ")
		fmt.Printf("%q \n", splitline)

		if splitline[0] == "toggle" {
			// Toggle lights
			s1 := strings.Split(splitline[1], ",")
			x_start, _ = strconv.Atoi(s1[0])
			y_start, _ = strconv.Atoi(s1[1])
			s2 := strings.Split(splitline[3], ",")
			x_end, _ = strconv.Atoi(s2[0])
			y_end, _ = strconv.Atoi(s2[1])
			for i := x_start; i <= x_end; i++ {
				for j := y_start; j <= y_end; j++ {
					lights[i][j] = !lights[i][j]
					// Part 2
					lights_p2[i][j] = lights_p2[i][j] + 2
				}
			}
		} else if splitline[0] == "turn" && splitline[1] == "on" {
			// Turn on lights
			s1 := strings.Split(splitline[2], ",")
			x_start, _ = strconv.Atoi(s1[0])
			y_start, _ = strconv.Atoi(s1[1])
			s2 := strings.Split(splitline[4], ",")
			x_end, _ = strconv.Atoi(s2[0])
			y_end, _ = strconv.Atoi(s2[1])
			for i := x_start; i <= x_end; i++ {
				for j := y_start; j <= y_end; j++ {
					lights[i][j] = true
					// Part 2
					lights_p2[i][j]++
				}
			}
		} else if splitline[0] == "turn" && splitline[1] == "off" {
			// Turn off lights
			s1 := strings.Split(splitline[2], ",")
			x_start, _ = strconv.Atoi(s1[0])
			y_start, _ = strconv.Atoi(s1[1])
			s2 := strings.Split(splitline[4], ",")
			x_end, _ = strconv.Atoi(s2[0])
			y_end, _ = strconv.Atoi(s2[1])
			for i := x_start; i <= x_end; i++ {
				for j := y_start; j <= y_end; j++ {
					lights[i][j] = false
					// Part 2
					lights_p2[i][j]--
					if lights_p2[i][j] < 0 {
						lights_p2[i][j] = 0
					}
				}
			}
		}
		//		fmt.Printf("x_start %d\n", x_start)
		//		fmt.Printf("y_start %d\n", y_start)
		//		fmt.Printf("x_end %d\n", x_end)
		//		fmt.Printf("y_end %d\n", y_end)

	}
	lightcount := 0
	brightness := 0
	for i := 0; i <= 999; i++ {
		for j := 0; j <= 999; j++ {
			if lights[i][j] {
				lightcount++
			}
			brightness = brightness + lights_p2[i][j]
		}
	}

	fmt.Println("Number of lights on: ", lightcount)
	fmt.Println("Brightness: ", brightness)

	counter := 0
	for i := 0; i <= 999; i++ {
		for j := 0; j <= 999; j++ {
			counter++
		}
	}

	fmt.Println("Counter: ", counter)

}