130 lines
2.5 KiB
Go
130 lines
2.5 KiB
Go
package main
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import (
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aoc "AoC/2021/common"
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"bufio"
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"strconv"
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)
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func processInput(input *bufio.Scanner) [10][10]int {
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var octopuses [10][10]int
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for y := 0; input.Scan(); y++ {
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line := input.Text()
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for x, c := range line {
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n, _ := strconv.Atoi(string(c))
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octopuses[y][x] = n
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}
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}
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return octopuses
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}
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func simulate(octopuses [10][10]int) ([10][10]int, int) {
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// Start with increasing all the energy levels by one
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counter := 0
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for y := 0; y < 10; y++ {
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for x := 0; x < 10; x++ {
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octopuses[y][x]++
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if octopuses[y][x] > 9 {
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counter++
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}
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}
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}
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// Increase the energy levels of neighbours if a flash has to occur
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// We keep doing this until the number of octopuses ready to flash does not increase
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flashes := 0
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for counter != 0 {
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for y := 0; y < 10; y++ {
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for x := 0; x < 10; x++ {
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if octopuses[y][x] > 9 {
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octopuses[y][x] = 0
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flashes++
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if x != 0 && octopuses[y][x-1] != 0 {
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octopuses[y][x-1]++
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}
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if x != 9 && octopuses[y][x+1] != 0 {
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octopuses[y][x+1]++
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}
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if y != 0 && octopuses[y-1][x] != 0 {
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octopuses[y-1][x]++
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}
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if y != 9 && octopuses[y+1][x] != 0 {
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octopuses[y+1][x]++
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}
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if x != 0 && y != 0 && octopuses[y-1][x-1] != 0 {
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octopuses[y-1][x-1]++
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}
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if x != 9 && y != 0 && octopuses[y-1][x+1] != 0 {
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octopuses[y-1][x+1]++
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}
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if x != 0 && y != 9 && octopuses[y+1][x-1] != 0 {
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octopuses[y+1][x-1]++
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}
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if x != 9 && y != 9 && octopuses[y+1][x+1] != 0 {
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octopuses[y+1][x+1]++
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}
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}
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}
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}
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counter = 0
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for y := 0; y < 10; y++ {
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for x := 0; x < 10; x++ {
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if octopuses[y][x] > 9 {
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counter++
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}
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}
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}
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}
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return octopuses, flashes
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}
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func main() {
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challenge := aoc.New(2021, 11)
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challenge.Test(`5483143223
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2745854711
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5264556173
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6141336146
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6357385478
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4167524645
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2176841721
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6882881134
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4846848554
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5283751526`, []int{1656, 195})
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challenge.Solution(1, func (input *bufio.Scanner) int {
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octopuses := processInput(input)
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sum := 0
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for step := 0; step < 100; step++ {
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var s int
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octopuses, s = simulate(octopuses)
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sum += s
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}
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return sum
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})
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challenge.Solution(2, func (input *bufio.Scanner) int {
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octopuses := processInput(input)
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for step := 0; step < 1000; step++ {
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var s int
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octopuses, s = simulate(octopuses)
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// Return the first step where all octopuses flash at the same time
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if s == 100 {
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// +1 is needed as we start counting at 0
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return step + 1
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}
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}
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return -2
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})
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}
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