2018 Day 22 Complete

2018/day22/map.go

@@ -0,0 +1,111 @@
+package main
+
+import "fmt"
+
+const (
+	geologicY  = 16807
+	geologicX  = 48271
+	caveModulo = 20183
+)
+
+const (
+	TypeRocky  = 0
+	TypeWet    = 1
+	TypeNarrow = 2
+)
+
+const (
+	ToolNone = 1 << iota
+	ToolTorch
+	ToolGear
+)
+
+type Map struct {
+	target               coord
+	depth                int
+	geologicIndicesCache map[int]map[int]int
+	erosionLevelsCache   map[int]map[int]int
+}
+
+func NewMap(input []string) *Map {
+	m := Map{}
+	m.geologicIndicesCache = make(map[int]map[int]int)
+	m.erosionLevelsCache = make(map[int]map[int]int)
+
+	if len(input) != 2 {
+		panic("Invalid Input")
+	}
+	_, err := fmt.Sscanf(input[0], "depth: %d", &m.depth)
+	if err != nil {
+		panic(err)
+	}
+	_, err = fmt.Sscanf(input[1], "target: %d,%d", &m.target.x, &m.target.y)
+	if err != nil {
+		panic(err)
+	}
+
+	return &m
+}
+
+func (m *Map) GeologicIndex(x, y int) int {
+	if m.geologicIndicesCache[y] != nil {
+		if i, ok := m.geologicIndicesCache[y][x]; ok {
+			return i
+		}
+	} else {
+		m.geologicIndicesCache[y] = make(map[int]int)
+	}
+
+	switch {
+	case x == 0 && y == 0, x == m.target.x && y == m.target.y:
+		m.geologicIndicesCache[y][x] = 0
+	case y == 0:
+		m.geologicIndicesCache[y][x] = x * geologicY
+	case x == 0:
+		m.geologicIndicesCache[y][x] = y * geologicX
+	default:
+		m.geologicIndicesCache[y][x] = m.ErosionLevel(x-1, y) * m.ErosionLevel(x, y-1)
+	}
+	return m.geologicIndicesCache[y][x]
+}
+
+func (m *Map) ErosionLevel(x, y int) int {
+	if m.erosionLevelsCache[y] != nil {
+		if level, ok := m.erosionLevelsCache[y][x]; ok {
+			return level
+		}
+	} else {
+		m.erosionLevelsCache[y] = make(map[int]int)
+	}
+	m.erosionLevelsCache[y][x] = (m.GeologicIndex(x, y) + m.depth) % caveModulo
+	return m.erosionLevelsCache[y][x]
+}
+
+func (m Map) Type(x, y int) int {
+	return m.ErosionLevel(x, y) % 3
+}
+
+func (m Map) Neighbors(pos coord, equip int) []Item {
+	var n []Item
+	for _, c := range pos.neighbors() {
+		t := m.Type(c.x, c.y)
+		if equip&allowed(t) != 0 {
+			n = append(n, Item{pos: c, equip: equip, time: 1})
+			n = append(n, Item{pos: c, equip: equip ^ allowed(t), time: 8})
+		}
+	}
+	return n
+}
+
+func allowed(regionType int) int {
+	switch regionType {
+	case TypeRocky:
+		return ToolGear | ToolTorch
+	case TypeWet:
+		return ToolGear | ToolNone
+	case TypeNarrow:
+		return ToolTorch | ToolNone
+	default:
+		panic(fmt.Errorf("unknown region type: %d", regionType))
+	}
+}