125 lines
2.2 KiB
Go
125 lines
2.2 KiB
Go
package main
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import (
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"fmt"
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h "git.bullercodeworks.com/brian/adventofcode/helpers"
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)
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const (
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White = iota
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Black
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)
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var tiles map[h.Coordinate]bool
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func init() {
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tiles = make(map[h.Coordinate]bool)
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}
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func main() {
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fmt.Println("# Day 22")
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inp := h.StdinToStringSlice()
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solve(inp, h.Atoi(h.OptArgNumber(1, "2")))
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}
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func solve(inp []string, part int) {
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buildTiles(inp)
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if part == 1 {
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fmt.Println("## Part 1\nAnswer:", len(tiles))
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} else {
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for day := 1; day <= 100; day++ {
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next := make(map[h.Coordinate]bool)
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lx, ly, hx, hy := getBordering()
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for y := ly; y <= hy; y++ {
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for x := lx; x <= hx; x++ {
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tst := h.Coordinate{X: x, Y: y}
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_, ok := tiles[tst]
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bl := CountTiles(GetAllNeighborCoords(tst))
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if (ok && !(bl == 0 || bl > 2)) || (!ok && bl == 2) {
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next[tst] = true
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}
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}
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}
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tiles = next
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fmt.Printf("Day %d: %d\n", day, len(next))
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}
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}
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}
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func getBordering() (int, int, int, int) {
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lx, ly, hx, hy := h.MAX_INT, h.MAX_INT, h.MIN_INT, h.MIN_INT
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for k := range tiles {
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lx = h.Min(lx, k.X)
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ly = h.Min(ly, k.Y)
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hx = h.Max(hx, k.X)
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hy = h.Max(hy, k.Y)
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}
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return lx - 1, ly - 1, hx + 1, hy + 1
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}
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/*
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o o
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o o o
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o o
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*/
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func buildTiles(inp []string) {
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for k := range inp {
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curr := h.Coordinate{}
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var last rune
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for _, r := range inp[k] {
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if r == 'n' || r == 's' {
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last = r
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continue
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}
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curr = GetNeighborCoord(curr, last+r)
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last = 0
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}
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if v := tiles[curr]; v {
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delete(tiles, curr)
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} else {
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tiles[curr] = true
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}
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}
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}
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func CountTiles(c []h.Coordinate) int {
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var ret int
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for _, v := range c {
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if _, ok := tiles[v]; ok {
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ret++
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}
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}
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return ret
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}
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func GetAllNeighborCoords(c h.Coordinate) []h.Coordinate {
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var ret []h.Coordinate
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for _, v := range []rune{
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'e', 'n' + 'e', 's' + 'e', 'w', 'n' + 'w', 's' + 'w',
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} {
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ret = append(ret, GetNeighborCoord(c, v))
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}
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return ret
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}
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// Translate hex neighbors into a 2d plane
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func GetNeighborCoord(c h.Coordinate, dir rune) h.Coordinate {
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switch dir {
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case 'e':
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return c.East()
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case 'n' + 'e':
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return c.North()
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case 's' + 'e':
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return c.South().East()
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case 'w':
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return c.West()
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case 'n' + 'w':
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return c.North().West()
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case 's' + 'w':
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return c.South()
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}
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return c
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}
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