2018 Day 15 Completed!

2019-11-07 09:36:24 -06:00
parent bd274c826c
commit f03772c578
7 changed files with 425 additions and 380 deletions
--- a/2018/day15/unit.go
+++ b/2018/day15/unit.go
@@ -0,0 +1,144 @@
+package main
+
+import (
+	"math"
+	"sort"
+)
+
+type Unit struct {
+	Kind      int
+	Hitpoints int
+	Power     int
+	Tile      *Tile
+}
+
+const (
+	defaultHitpoints = 200
+	defaultPower     = 3
+)
+
+type SortableUnits []*Unit
+
+func (s SortableUnits) Len() int {
+	return len(s)
+}
+func (s SortableUnits) Less(i, j int) bool {
+	if s[i].Tile.Y == s[j].Tile.Y {
+		return s[i].Tile.X < s[j].Tile.X
+	}
+	return s[i].Tile.Y < s[j].Tile.Y
+}
+
+func (s SortableUnits) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+
+func NewUnit(tile *Tile, kind, elfPower int) *Unit {
+	unit := &Unit{
+		Kind:      kind,
+		Hitpoints: defaultHitpoints,
+		Power:     defaultPower,
+		Tile:      tile,
+	}
+	tile.Unit = unit
+	if unit.Kind == KindElf {
+		unit.Power = elfPower
+	}
+	return unit
+}
+
+func (u Unit) Targets(c *Cave) bool {
+	for _, unit := range c.Units {
+		if unit.Kind != u.Kind && unit.Hitpoints > 0 {
+			return true
+		}
+	}
+	return false
+}
+
+// NextTile returns the next tile to move to and the target tile (or nil if no target found)
+func (u *Unit) NextTile(c *Cave) (*Tile, *Tile) {
+	var targets SortableTiles
+	closestTargetDistance := math.MaxInt32
+	distances, path := c.Map.FindWalkableTiles(u.Tile)
+	enemies := u.Enemies(c)
+	for _, enemy := range enemies {
+		for _, target := range enemy.Tile.WalkableNeighbors() {
+			if distance, ok := distances[target]; ok && distance <= closestTargetDistance {
+				if distance < closestTargetDistance {
+					closestTargetDistance = distance
+					targets = SortableTiles{}
+				}
+				targets = append(targets, target)
+			}
+		}
+	}
+	sort.Sort(targets)
+	if len(targets) > 0 {
+		target := targets[0]
+		current := target
+		for {
+			if path[current] == u.Tile {
+				return current, target
+			}
+			current = path[current]
+		}
+	}
+	return nil, nil
+}
+
+// Enemies returns enemy units sorted by map position in reading order
+func (u *Unit) Enemies(c *Cave) SortableUnits {
+	var enemies SortableUnits
+	for _, unit := range c.Units {
+		if unit.Kind != u.Kind && unit.Hitpoints > 0 {
+			enemies = append(enemies, unit)
+		}
+	}
+	sort.Sort(enemies)
+	return enemies
+}
+
+func (u *Unit) EnemyNeighbor(c *Cave) *Unit {
+	var target *Unit
+	for _, offset := range offsets {
+		if t := c.Map.Tile(u.Tile.X+offset.X, u.Tile.Y+offset.Y); t != nil && t.Unit != nil && t.Unit.Kind != u.Kind && t.Unit.Hitpoints > 0 {
+			if target == nil || t.Unit.Hitpoints < target.Hitpoints {
+				target = t.Unit
+			}
+		}
+	}
+	return target
+}
+
+func (u *Unit) Move(c *Cave) {
+	if u.EnemyNeighbor(c) != nil {
+		return
+	}
+	next, _ := u.NextTile(c)
+	if next != nil {
+		next.Unit = u
+		next.Kind = u.Kind
+		u.Tile.Kind = KindSpace
+		u.Tile.Unit = nil
+		u.Tile = next
+	}
+}
+
+func (u *Unit) Attack(c *Cave) bool {
+	enemy := u.EnemyNeighbor(c)
+	if enemy != nil {
+		killed := enemy.Damage(c, u.Power)
+		return killed && enemy.Kind == KindElf
+	}
+	return false
+}
+
+func (u *Unit) Damage(c *Cave, damage int) bool {
+	u.Hitpoints = u.Hitpoints - damage
+	if u.Hitpoints <= 0 {
+		c.RemoveUnit(u)
+		return true
+	}
+	return false
+}