mirror of
https://github.com/Threnklyn/advent-of-code-go.git
synced 2026-06-07 12:45:10 +02:00
2023-19 not the prettiest recursion...
This commit is contained in:
alexchao26
@@ -0,0 +1,240 @@
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package main
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import (
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_ "embed"
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"flag"
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"fmt"
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"strings"
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"github.com/alexchao26/advent-of-code-go/cast"
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"github.com/alexchao26/advent-of-code-go/util"
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)
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//go:embed input.txt
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var input string
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func init() {
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// do this in init (not main) so test file has same input
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input = strings.TrimRight(input, "\n")
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if len(input) == 0 {
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panic("empty input.txt file")
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}
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}
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func main() {
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var part int
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flag.IntVar(&part, "part", 1, "part 1 or 2")
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flag.Parse()
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fmt.Println("Running part", part)
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if part == 1 {
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ans := part1(input)
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util.CopyToClipboard(fmt.Sprintf("%v", ans))
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fmt.Println("Output:", ans)
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} else {
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ans := part2(input)
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util.CopyToClipboard(fmt.Sprintf("%v", ans))
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fmt.Println("Output:", ans)
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}
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}
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func part1(input string) int {
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parts, workflowsMap := parseInput(input)
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ans := 0
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for _, p := range parts {
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currentWorkflowName := "in"
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for currentWorkflowName != "A" && currentWorkflowName != "R" {
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wf := workflowsMap[currentWorkflowName]
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for _, rule := range wf.ruleStrings {
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if !strings.Contains(rule, ":") {
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currentWorkflowName = rule
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break
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}
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colonSplit := strings.Split(rule, ":")
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output := colonSplit[1]
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if strings.Contains(colonSplit[0], "<") {
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conditionalParts := strings.Split(colonSplit[0], "<")
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if p[conditionalParts[0]] < cast.ToInt(conditionalParts[1]) {
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currentWorkflowName = output
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break
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}
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} else if strings.Contains(colonSplit[0], ">") {
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conditionalParts := strings.Split(colonSplit[0], ">")
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if p[conditionalParts[0]] > cast.ToInt(conditionalParts[1]) {
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currentWorkflowName = output
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break
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}
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} else {
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panic("unexpected workflow rule conditional: " + rule)
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}
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}
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}
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if currentWorkflowName == "A" {
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ans += p.sumRatings()
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}
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}
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return ans
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}
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type part map[string]int
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func (p part) sumRatings() int {
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total := 0
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for _, v := range p {
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total += v
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}
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return total
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}
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type workflow struct {
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name string
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ruleStrings []string
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}
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func parseInput(input string) (parts []part, workflowsMap map[string]workflow) {
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inputParts := strings.Split(input, "\n\n")
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workflowsMap = map[string]workflow{}
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// process workflows
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for _, line := range strings.Split(inputParts[0], "\n") {
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lineParts := strings.Split(line, "{")
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wf := workflow{
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name: lineParts[0],
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ruleStrings: strings.Split(lineParts[1][:len(lineParts[1])-1], ","),
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}
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workflowsMap[wf.name] = wf
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}
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for _, line := range strings.Split(inputParts[1], "\n") {
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withoutBraces := line[1 : len(line)-1]
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p := part{}
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for _, ratingStr := range strings.Split(withoutBraces, ",") {
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ratingParts := strings.Split(ratingStr, "=")
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p[ratingParts[0]] = cast.ToInt(ratingParts[1])
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}
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parts = append(parts, p)
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}
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return parts, workflowsMap
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}
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func part2(input string) int {
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_, workflowsMap := parseInput(input)
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// 1 to 4000 bounds for each rating...
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boundedParts := map[string][2]int{
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"x": {1, 4000},
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"m": {1, 4000},
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"a": {1, 4000},
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"s": {1, 4000},
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}
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return updatePartBoundsAndSplit(boundedParts, workflowsMap, "in", 0)
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}
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func updatePartBoundsAndSplit(boundedParts map[string][2]int, workflowsMap map[string]workflow, currentWorkflow string, debugDepth int) int {
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if currentWorkflow == "R" {
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return 0
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}
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if currentWorkflow == "A" {
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product := 1
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for _, bounds := range boundedParts {
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product *= bounds[1] - bounds[0] + 1
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}
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return product
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}
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// split based on rules...
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total := 0
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// for each rule,
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// the rule either passes and moves onto a different workflow,
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// or fails and checks the next rule
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// need to sum up both forks
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//
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// passing is handled via recursion, failing is handled via looping to the next rule
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// in both cases the bounds need to be updated
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for _, rule := range workflowsMap[currentWorkflow].ruleStrings {
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// just the next workflow to go after
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if !strings.Contains(rule, ":") {
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nextWorkflowName := rule
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total += updatePartBoundsAndSplit(boundedParts, workflowsMap, nextWorkflowName, debugDepth+1)
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break
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}
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colonSplit := strings.Split(rule, ":")
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nextWorkflowName := colonSplit[1]
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if strings.Contains(colonSplit[0], "<") {
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conditionalParts := strings.Split(colonSplit[0], "<")
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ratingName := conditionalParts[0]
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ratingTestValue := cast.ToInt(conditionalParts[1])
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// fork the part that passes the < conditional
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copyOfBounds := copyBoundedPartsMap(boundedParts)
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copyOfBounds[ratingName] = [2]int{
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copyOfBounds[ratingName][0],
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ratingTestValue - 1,
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}
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// check that the new bounds are still valid
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if copyOfBounds[ratingName][0] <= copyOfBounds[ratingName][1] {
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total += updatePartBoundsAndSplit(copyOfBounds, workflowsMap, nextWorkflowName, debugDepth+1)
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}
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// second fork for failing the conditional, need to update the boundedParts to fail
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boundedParts[ratingName] = [2]int{
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ratingTestValue,
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boundedParts[ratingName][1],
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}
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// check that the new bounds are still valid
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if boundedParts[ratingName][0] > boundedParts[ratingName][1] {
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break
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}
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} else if strings.Contains(colonSplit[0], ">") {
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conditionalParts := strings.Split(colonSplit[0], ">")
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ratingName := conditionalParts[0]
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ratingTestValue := cast.ToInt(conditionalParts[1])
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// fork the part that passes the > conditional
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copyOfBounds := copyBoundedPartsMap(boundedParts)
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copyOfBounds[ratingName] = [2]int{
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ratingTestValue + 1,
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copyOfBounds[ratingName][1],
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}
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// check that the new bounds are still valid before recursing
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if copyOfBounds[ratingName][0] <= copyOfBounds[ratingName][1] {
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total += updatePartBoundsAndSplit(copyOfBounds, workflowsMap, nextWorkflowName, debugDepth+1)
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}
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// second fork for failing the conditional, need to update the boundedParts to fail
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boundedParts[ratingName] = [2]int{
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boundedParts[ratingName][0],
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ratingTestValue,
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}
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// check that the new bounds are still valid
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if boundedParts[ratingName][0] > boundedParts[ratingName][1] {
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break
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}
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} else {
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panic("unexpected workflow rule conditional: " + rule)
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}
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}
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return total
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}
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func copyBoundedPartsMap(boundedParts map[string][2]int) map[string][2]int {
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cp := map[string][2]int{}
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for k, v := range boundedParts {
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cp[k] = v
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}
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return cp
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}
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