feat(2020-24/angch): redblobgames rocks

Author: angch

2020-24/angch/main.go

@@ -0,0 +1,163 @@
+package main
+
+import (
+	"bufio"
+	"log"
+	"os"
+)
+
+type Hex struct {
+	I, J, K int
+}
+
+func Cube(i, j, k int) Hex {
+	return Hex{i, j, k}
+}
+
+var dir = map[string]Hex{
+	"e":  Cube(+1, -1, 0),
+	"ne": Cube(+1, 0, -1),
+	"nw": Cube(0, +1, -1),
+	"w":  Cube(-1, +1, 0),
+	"sw": Cube(-1, 0, +1),
+	"se": Cube(0, -1, +1),
+}
+
+func do(fileName string) (ret1 int, ret2 int) {
+	file, err := os.Open(fileName)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer file.Close()
+	scanner := bufio.NewScanner(file)
+
+	current := Hex{}
+	hexmap := make(map[Hex]bool)
+
+	for scanner.Scan() {
+		l := scanner.Text()
+		_ = l
+
+		p := ""
+		current = Hex{}
+		for _, v := range l {
+			if v == 'e' || v == 'w' {
+				d := p + string(v)
+				dh, ok := dir[d]
+				if !ok {
+					log.Fatal(dh)
+				}
+				current.I += dh.I
+				current.J += dh.J
+				current.K += dh.K
+				p = ""
+			} else {
+				p = string(v)
+			}
+		}
+		hexmap[current] = !hexmap[current]
+
+	}
+
+	// log.Println(hexmap)
+
+	for _, v := range hexmap {
+		if v {
+			ret1++
+		}
+	}
+
+	for day := 1; day <= 100; day++ {
+		hexmap2 := make(map[Hex]bool)
+		min, max := minmax(hexmap)
+		for i := min.I - 1; i <= max.I+1; i++ {
+			for j := min.J - 1; j <= max.J+1; j++ {
+				for k := min.K - 1; k <= max.K+1; k++ {
+					c := Hex{i, j, k}
+					n := neighbour(hexmap, c)
+					if hexmap[c] {
+						if n == 0 || n > 2 {
+							// hexmap2[c] = false
+						} else {
+							hexmap2[c] = true
+						}
+					} else {
+						if n == 2 {
+							hexmap2[c] = true
+						} else {
+							// hexmap2[c] = false
+						}
+					}
+				}
+			}
+		}
+		hexmap = hexmap2
+
+		count := 0
+		for _, v := range hexmap {
+			if v {
+				count++
+			}
+		}
+		ret2 = count
+		log.Println("Day", day, count)
+
+	}
+
+	return ret1, ret2
+}
+
+func minmax(hexmap map[Hex]bool) (Hex, Hex) {
+	min := Hex{}
+	max := Hex{}
+	first := true
+	for k, v := range hexmap {
+		if !v {
+			continue
+		}
+		if first {
+			first = false
+			min = k
+			max = k
+			continue
+		}
+		if min.I > k.I {
+			min.I = k.I
+		}
+		if min.J > k.J {
+			min.J = k.J
+		}
+		if min.K > k.K {
+			min.K = k.K
+		}
+		if max.I < k.I {
+			max.I = k.I
+		}
+		if max.J < k.J {
+			max.J = k.J
+		}
+		if max.K < k.K {
+			max.K = k.K
+		}
+	}
+	return min, max
+}
+
+func neighbour(hexmap map[Hex]bool, c Hex) int {
+	count := 0
+	for _, v := range dir {
+		d := c
+		d.I += v.I
+		d.J += v.J
+		d.K += v.K
+
+		if hexmap[d] {
+			count++
+		}
+	}
+	return count
+}
+func main() {
+	log.Println(do("test.txt"))
+	log.Println(do("input.txt"))
+}

2020-24/angch/test.txt

@@ -0,0 +1,20 @@
+sesenwnenenewseeswwswswwnenewsewsw
+neeenesenwnwwswnenewnwwsewnenwseswesw
+seswneswswsenwwnwse
+nwnwneseeswswnenewneswwnewseswneseene
+swweswneswnenwsewnwneneseenw
+eesenwseswswnenwswnwnwsewwnwsene
+sewnenenenesenwsewnenwwwse
+wenwwweseeeweswwwnwwe
+wsweesenenewnwwnwsenewsenwwsesesenwne
+neeswseenwwswnwswswnw
+nenwswwsewswnenenewsenwsenwnesesenew
+enewnwewneswsewnwswenweswnenwsenwsw
+sweneswneswneneenwnewenewwneswswnese
+swwesenesewenwneswnwwneseswwne
+enesenwswwswneneswsenwnewswseenwsese
+wnwnesenesenenwwnenwsewesewsesesew
+nenewswnwewswnenesenwnesewesw
+eneswnwswnwsenenwnwnwwseeswneewsenese
+neswnwewnwnwseenwseesewsenwsweewe
+wseweeenwnesenwwwswnew