127 lines
2.2 KiB
Go
127 lines
2.2 KiB
Go
package main
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import (
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"fmt"
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"os"
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"git.annabunch.es/annabunches/adventofcode/2020/lib/util"
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)
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func occupied1(board [][]byte, i, j int) int {
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if i < 0 || j < 0 || i >= len(board) || j >= len(board[0]) {
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return 0
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}
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if board[i][j] == '#' {
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return 1
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}
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return 0
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}
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func occupied2(board [][]byte, i, j, iDir, jDir, level int) int {
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si := i + (iDir * level)
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sj := j + (jDir * level)
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if si < 0 || sj < 0 || si >= len(board) || sj >= len(board[0]) {
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return 0
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}
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if board[si][sj] == 'L' {
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return 0
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}
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if board[si][sj] == '#' {
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return 1
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}
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return occupied2(board, i, j, iDir, jDir, level+1)
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}
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func getNewValue(board [][]byte, i, j int, step string) byte {
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if board[i][j] == '.' {
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return '.'
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}
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occ := 0
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occLimit := 4
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switch step {
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case "1":
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occ = occupied1(board, i-1, j-1) +
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occupied1(board, i-1, j) +
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occupied1(board, i-1, j+1) +
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occupied1(board, i, j-1) +
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occupied1(board, i, j+1) +
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occupied1(board, i+1, j-1) +
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occupied1(board, i+1, j) +
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occupied1(board, i+1, j+1)
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case "2":
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occLimit = 5
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occ = occupied2(board, i, j, -1, -1, 1) +
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occupied2(board, i, j, -1, 0, 1) +
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occupied2(board, i, j, -1, +1, 1) +
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occupied2(board, i, j, 0, -1, 1) +
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occupied2(board, i, j, 0, +1, 1) +
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occupied2(board, i, j, 1, -1, 1) +
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occupied2(board, i, j, 1, 0, 1) +
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occupied2(board, i, j, 1, +1, 1)
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}
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if board[i][j] == 'L' && occ == 0 {
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return '#'
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}
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if board[i][j] == '#' && occ >= occLimit {
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return 'L'
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}
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return board[i][j]
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}
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func countOccupied(board [][]byte) int {
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count := 0
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for i := 0; i < len(board); i++ {
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for j := 0; j < len(board[0]); j++ {
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if board[i][j] == '#' {
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count++
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}
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}
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}
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return count
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}
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func main() {
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step := os.Args[1]
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board := util.InputParserBytes(os.Args[2])
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changed := true
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for changed {
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changed = false
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// initialize the next generation
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newBoard := make([][]byte, len(board))
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for i := 0; i < len(newBoard); i++ {
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newBoard[i] = make([]byte, len(board[0]))
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copy(newBoard[i], board[i])
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}
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for i := 0; i < len(board); i++ {
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for j := 0; j < len(board[0]); j++ {
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value := getNewValue(board, i, j, step)
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if board[i][j] != value {
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newBoard[i][j] = value
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changed = true
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}
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}
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}
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board = newBoard
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}
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fmt.Println(countOccupied(board))
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}
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