2021 Day 22 Complete!

2021/day22/main.go

@@ -0,0 +1,179 @@
+package main
+
+import (
+	"fmt"
+	"strings"
+
+	h "git.bullercodeworks.com/brian/adventofcode/helpers"
+)
+
+var steps []cuboid
+
+func main() {
+	inp := h.StdinToStringSlice()
+	for i := range inp {
+		pts := strings.Split(inp[i], " ")
+		c := strings.Split(pts[1], ",")
+		steps = append(steps, NewCuboid(
+			pts[0] == "on",
+			c[0][2:],
+			c[1][2:],
+			c[2][2:],
+		))
+	}
+	m := c3dMap{
+		Field: make(map[h.Coordinate3d]bool),
+		blfX:  -50, trbX: 50,
+		blfY: -50, trbY: 50,
+		blfZ: -50, trbZ: 50,
+	}
+	initialize(&m)
+	reboot()
+}
+
+func initialize(m *c3dMap) {
+	fmt.Println("# Part 1")
+	for i := range steps {
+		m.doInitialize(steps[i])
+	}
+	fmt.Printf("After initialization, %d bits are on.\n", m.count(true))
+}
+
+func reboot() {
+	fmt.Println("# Part 2")
+	var cuboids []cuboid
+	var volume int64
+	for _, s1 := range steps {
+		adds := make([]cuboid, 0)
+		if s1.val {
+			adds = append(adds, s1)
+		}
+		for _, s2 := range cuboids {
+			if i := s1.intersect(s2, !s2.val); i.valid() {
+				adds = append(adds, i)
+			}
+		}
+		cuboids = append(cuboids, adds...)
+	}
+	for _, c := range cuboids {
+		if c.val {
+			volume += c.volume()
+		} else {
+			volume -= c.volume()
+		}
+	}
+	fmt.Printf("After reboot, %d bits are on.\n", volume)
+}
+
+type cuboid struct {
+	val    bool
+	x1, x2 int
+	y1, y2 int
+	z1, z2 int
+}
+
+func NewCuboid(val bool, x, y, z string) cuboid {
+	s := cuboid{val: val}
+	fmt.Sscanf(x, "%d..%d", &s.x1, &s.x2)
+	fmt.Sscanf(y, "%d..%d", &s.y1, &s.y2)
+	fmt.Sscanf(z, "%d..%d", &s.z1, &s.z2)
+	return s
+}
+
+func (s cuboid) volume() int64 {
+	return int64((h.Abs(s.x2-s.x1) + 1) * (h.Abs(s.y2-s.y1) + 1) * (h.Abs(s.z2-s.z1) + 1))
+}
+func (s cuboid) valid() bool {
+	return s.x1 <= s.x2 && s.y1 <= s.y2 && s.z1 <= s.z2
+}
+func (s cuboid) intersect(t cuboid, val bool) cuboid {
+	return cuboid{
+		val: val,
+		x1:  h.Max(s.x1, t.x1),
+		x2:  h.Min(s.x2, t.x2),
+		y1:  h.Max(s.y1, t.y1),
+		y2:  h.Min(s.y2, t.y2),
+		z1:  h.Max(s.z1, t.z1),
+		z2:  h.Min(s.z2, t.z2),
+	}
+}
+func (s cuboid) String() string {
+	return fmt.Sprintf("{%v; x:%d..%d, y:%d..%d, z:%d..%d}", s.val, s.x1, s.x2, s.y1, s.y2, s.z1, s.z2)
+}
+
+// Ended up not even using this for part 2
+type c3dMap struct {
+	Field      map[h.Coordinate3d]bool
+	blfX, trbX int
+	blfY, trbY int
+	blfZ, trbZ int
+}
+
+func (c *c3dMap) count(v bool) int {
+	var ret int
+	for x := c.blfX; x <= c.trbX; x++ {
+		for y := c.blfY; y <= c.trbY; y++ {
+			for z := c.blfZ; z <= c.trbZ; z++ {
+				if c.Field[h.Coordinate3d{X: x, Y: y, Z: z}] == v {
+					ret++
+				}
+			}
+		}
+	}
+	return ret
+}
+
+func (c *c3dMap) doInitialize(s cuboid) {
+	if !c.inRange(s) {
+		return
+	}
+	c.do(s)
+}
+
+func (c *c3dMap) do(s cuboid) {
+	for x := s.x1; x <= s.x2; x++ {
+		if x < c.blfX || x > c.trbX {
+			continue
+		}
+		for y := s.y1; y <= s.y2; y++ {
+			if y < c.blfY || x > c.trbY {
+				continue
+			}
+			for z := s.z1; z <= s.z2; z++ {
+				if z < c.blfZ || x > c.trbZ {
+					continue
+				}
+				c.Field[h.Coordinate3d{X: x, Y: y, Z: z}] = s.val
+			}
+		}
+	}
+}
+
+func (c *c3dMap) inRange(s cuboid) bool {
+	if s.x2 < c.blfX {
+		return false
+	}
+	if s.x1 > c.trbX {
+		return false
+	}
+	if s.y2 < c.blfY {
+		return false
+	}
+	if s.y1 > c.trbY {
+		return false
+	}
+	if s.z2 < c.blfZ {
+		return false
+	}
+	if s.z1 > c.trbZ {
+		return false
+	}
+	return true
+}
+
+func (c c3dMap) Meta() string {
+	return fmt.Sprintf(
+		"{x: %d..%d, y: %d..%d, z: %d..%d}",
+		c.blfX, c.trbX, c.blfY, c.trbY, c.blfZ, c.trbZ,
+	)
+}