aoc2015/day22/day.go

package day22

import (
	"math"
	"strconv"
	"strings"
	"tools"
)

/*
Spells:
	Magic Missile - 53 Mana - 4 Damage
	Drain - 73 Mana - 2 Damage, 2 Heal
	Shield - 113 Mana - 7 Armor for 6 turns
	Poison - 173 Mana - 3 Damage per turn for 6 turns
	Recharge - 229 Mana - 101 Mana per turn for 5 turns
*/

type Entity struct {
	hitpoints int
	mana      int
	armor     int
	damage    int
}

var spells = map[string]string{
	"mm": "Magic Missile",
	"d":  "Drain",
	"s":  "Shield",
	"rc": "Recharge",
	"p":  "Poison",
}
var minWinningMana int

func applyEffects(player, boss Entity, effects map[string]int) (Entity, Entity, map[string]int) {
	for e, t := range effects {
		t--
		switch e {
		case "rc":
			player.mana += 101
			// fmt.Println("Recharge provides 101 mana; it's timer is now ", t)
		case "p":
			boss.hitpoints -= 3
			// fmt.Println("Poison deals 3 damage; it's timer is now ", t)
		case "s":
			if t == 0 {
				player.armor -= 7
			}
			// fmt.Println("Shield's timer is now ", t)
		}
		if t == 0 {
			// fmt.Println(spells[e], " wears off.")
			delete(effects, e)
		} else {
			effects[e] = t
		}
	}

	return player, boss, effects
}

func turn(player, boss Entity, effects map[string]int, spell string, hardmode bool) (Entity, Entity, map[string]int, int, int) {
	// return values: -1 player dead; 0 both alive; 1 boss dead
	/*
		fmt.Println("-- Player Turn --")
		fmt.Println("- Player has ", player.hitpoints, "hit points, ", player.armor, " armor, ", player.mana, " mana")
		fmt.Println("- Boss  has ", boss.hitpoints, " hit points")
	*/
	if hardmode {
		player.hitpoints -= 1
		if player.hitpoints <= 0 {
			return player, boss, effects, 0, -1
		}
	}
	// Apply effects, if any
	player, boss, effects = applyEffects(player, boss, effects)
	// Player cast spell -- which one?
	if _, ok := effects[spell]; ok {
		// cannot cast already active effect; how to fail?
		// just pretend the player died ...
		return player, boss, effects, 0, -1
	}
	var manaUsed int
	switch spell {
	case "mm":
		// fmt.Println("Player casts Magic Missile; dealing 4 damage.")
		boss.hitpoints -= 4
		manaUsed = 53
	case "d":
		// fmt.Println("Player casts Drain; dealing 2 damage and healing 2 hit points.")
		player.hitpoints += 2
		boss.hitpoints -= 2
		manaUsed = 73
	case "p":
		// fmt.Println("Player casts Poison.")
		effects[spell] = 6
		manaUsed = 173
	case "s":
		// fmt.Println("Player casts Shield.")
		player.armor += 7
		manaUsed = 113
		effects[spell] = 6
	case "rc":
		// fmt.Println("Player casts recharge.")
		manaUsed = 229
		effects[spell] = 5
	}
	player.mana -= manaUsed
	if player.mana <= 0 {
		return player, boss, effects, manaUsed, -1
	}

	// Check Boss health
	if boss.hitpoints <= 0 {
		return player, boss, effects, manaUsed, 1
	}

	/*
		fmt.Println("-- Boss Turn --")
		fmt.Println("- Player has ", player.hitpoints, "hit points, ", player.armor, " armor, ", player.mana, " mana")
		fmt.Println("- Boss  has ", boss.hitpoints, " hit points")
	*/
	// Apply effects, if any
	player, boss, effects = applyEffects(player, boss, effects)
	// Check Boss health
	if boss.hitpoints <= 0 {
		return player, boss, effects, manaUsed, 1
	}

	bossDamage := int(math.Max(1.0, float64(boss.damage-player.armor)))
	// fmt.Println("Boss attacks for ", bossDamage, " damage.")
	// Check Player health
	player.hitpoints -= bossDamage
	if player.hitpoints <= 0 {
		return player, boss, effects, manaUsed, -1
	}

	return player, boss, effects, manaUsed, 0
}

func findLowestManaUsed(player, boss Entity, effects map[string]int, manaUsed int, spellsUsed string, hardmode bool, depth int) (int, string) {
	minManaUsed := math.MaxInt32
	var minSpellsUsed string
	for s := range spells {
		var thisManaUse, state int
		thisPlayer := player
		thisBoss := boss
		thisEffects := make(map[string]int)
		thisSpells := spellsUsed + "," + s
		for e, t := range effects {
			thisEffects[e] = t
		}
		thisPlayer, thisBoss, thisEffects, thisManaUse, state = turn(thisPlayer, thisBoss, thisEffects, s, hardmode)
		switch state {
		case -1:
			continue
		case 0:
			if thisManaUse+manaUsed < minWinningMana {
				thisManaUse, thisSpells = findLowestManaUsed(thisPlayer, thisBoss, thisEffects, thisManaUse+manaUsed, thisSpells, hardmode, depth+1)
			} else {
				continue
			}
		case 1:
			if manaUsed+thisManaUse < minWinningMana {
				minWinningMana = manaUsed + thisManaUse
			}
		}
		if thisManaUse < minManaUsed {
			minManaUsed = thisManaUse
			minSpellsUsed = thisSpells
		}
	}
	return minManaUsed + manaUsed, minSpellsUsed
}

func Part1(puzzle tools.AoCPuzzle) interface{} {
	player := Entity{50, 500, 0, 0}
	boss := Entity{0, 0, 0, 0}
	bossData := puzzle.GetInputArray()
	for _, line := range bossData {
		parts := strings.Split(line, ": ")
		switch parts[0] {
		case "Hit Points":
			boss.hitpoints, _ = strconv.Atoi(parts[1])
		case "Damage":
			boss.damage, _ = strconv.Atoi(parts[1])
		}
	}

	effects := make(map[string]int)
	minWinningMana = math.MaxInt32

	findLowestManaUsed(player, boss, effects, 0, "", false, 0)
	return minWinningMana
}

func Part2(puzzle tools.AoCPuzzle) interface{} {
	player := Entity{50, 500, 0, 0}
	boss := Entity{0, 0, 0, 0}
	bossData := puzzle.GetInputArray()
	for _, line := range bossData {
		parts := strings.Split(line, ": ")
		switch parts[0] {
		case "Hit Points":
			boss.hitpoints, _ = strconv.Atoi(parts[1])
		case "Damage":
			boss.damage, _ = strconv.Atoi(parts[1])
		}
	}

	effects := make(map[string]int)
	minWinningMana = math.MaxInt32

	findLowestManaUsed(player, boss, effects, 0, "", true, 0)
	return minWinningMana
}