advent2022/solutions/day19/day19.go

package day19

import (
	"bufio"
	"fmt"
	"os"
)

type Blueprint struct {
	blueprintNumber   int
	oreRobotOreCost   int
	clayRobotOreCost  int
	obsRobotOreCost   int
	obsRobotClayCost  int
	geodeRobotOreCost int
	geodeRobotObsCost int
}

type State struct {
	minute   int
	ore      int
	clay     int
	obsidian int
	geodes   int

	oreRobots      int
	clayRobots     int
	obsidianRobots int
	geodeRobots    int
}

var initialState State = State{0, 0, 0, 0, 0, 1, 0, 0, 0}

func copyState(state State) State {
	return State{
		state.minute,
		state.ore,
		state.clay,
		state.obsidian,
		state.geodes,
		state.oreRobots,
		state.clayRobots,
		state.obsidianRobots,
		state.geodeRobots,
	}
}

func nextStates(current State, minutes int, blueprint Blueprint) []State {
	if current.minute == minutes {
		return []State{}
	}

	buyNothing := State{
		current.minute + 1,
		current.ore + current.oreRobots,
		current.clay + current.clayRobots,
		current.obsidian + current.obsidianRobots,
		current.geodes + current.geodeRobots,
		current.oreRobots,
		current.clayRobots,
		current.obsidianRobots,
		current.geodeRobots,
	}

	retval := []State{buyNothing}

	if current.ore >= blueprint.oreRobotOreCost {
		buyOre := copyState(buyNothing)
		buyOre.ore -= blueprint.oreRobotOreCost
		buyOre.oreRobots += 1
		retval = append(retval, buyOre)
	}

	if current.ore >= blueprint.clayRobotOreCost {
		buyClay := copyState(buyNothing)
		buyClay.ore -= blueprint.clayRobotOreCost
		buyClay.clayRobots += 1
		retval = append(retval, buyClay)
	}

	if current.ore >= blueprint.obsRobotOreCost && current.clay >= blueprint.obsRobotClayCost {
		buyObsidian := copyState(buyNothing)
		buyObsidian.ore -= blueprint.obsRobotOreCost
		buyObsidian.clay -= blueprint.obsRobotClayCost
		buyObsidian.obsidianRobots += 1
		retval = append(retval, buyObsidian)
	}

	if current.ore >= blueprint.geodeRobotOreCost && current.obsidian >= blueprint.geodeRobotObsCost {
		buyGeode := copyState(buyNothing)
		buyGeode.ore -= blueprint.geodeRobotOreCost
		buyGeode.obsidian -= blueprint.geodeRobotObsCost
		buyGeode.geodeRobots += 1
		retval = append(retval, buyGeode)
	}

	return retval
}

func runSimulation(blueprint Blueprint, minutes int) int {
	visited := map[State]bool{}
	queue := []State{initialState}
	bestResult := 0

	for len(queue) > 0 {
		nextState := queue[len(queue)-1]
		queue = queue[0 : len(queue)-1]

		_, alreadyDone := visited[nextState]
		if alreadyDone {
			continue
		}
		visited[nextState] = true

		minutesLeft := minutes - nextState.minute
		bestPossibleFuture := nextState.geodes + (minutesLeft*(2*nextState.geodeRobots+(minutesLeft-1)))/2
		if bestPossibleFuture < bestResult {
			continue
		}

		newStates := nextStates(nextState, minutes, blueprint)
		if len(newStates) == 0 {
			if nextState.geodes > bestResult {
				bestResult = nextState.geodes
			}
		}
		queue = append(queue, newStates...)
	}

	return bestResult
}

func Run(filename string) {
	file, err := os.Open(filename)
	if err != nil {
		fmt.Println("Error opening file:", err)
		return
	}

	scanner := bufio.NewScanner(file)
	scanner.Split(bufio.ScanLines)
	blueprints := []Blueprint{}

	for scanner.Scan() {
		line := scanner.Text()
		var blueprintNumber, oreRobotOre, clayRobotOre, obsRobotOre, obsRobotClay, geodeRobotOre, geodeRobotObs int
		fmt.Sscanf(line, "Blueprint %d: Each ore robot costs %d ore. Each clay robot costs %d ore. Each obsidian robot costs %d ore and %d clay. Each geode robot costs %d ore and %d obsidian.", &blueprintNumber, &oreRobotOre, &clayRobotOre, &obsRobotOre, &obsRobotClay, &geodeRobotOre, &geodeRobotObs)
		blueprints = append(blueprints, Blueprint{blueprintNumber, oreRobotOre, clayRobotOre, obsRobotOre, obsRobotClay, geodeRobotOre, geodeRobotObs})
	}
	file.Close()

	fmt.Println("Blueprints", blueprints)
	totalQualityLevel := 0
	for _, blueprint := range blueprints {
		geodesHarvested := runSimulation(blueprint, 24)
		fmt.Println("Found", geodesHarvested, "geodes for blueprint", blueprint.blueprintNumber)
		totalQualityLevel += geodesHarvested * blueprint.blueprintNumber
	}
	fmt.Println("Total quality level of all blueprints at 24 minutes is", totalQualityLevel)

	multipliedGeodes := 1
	if len(blueprints) > 3 {
		blueprints = blueprints[0:3]
	}
	for _, blueprint := range blueprints {
		geodesHarvested := runSimulation(blueprint, 32)
		fmt.Println("Found", geodesHarvested, "geodes for blueprint", blueprint.blueprintNumber)
		multipliedGeodes *= geodesHarvested
	}
	fmt.Println("Multiplied number of geodes of first three blueprints at 32 minutes is", multipliedGeodes)
}