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Cleanup

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This commit is contained in:
Sven Weidauer 2020-12-19 13:20:10 +01:00
parent 7c7d772ff5
commit 7a3715f1f4
1 changed files with 11 additions and 17 deletions
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28
day19/main.swift
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@ -75,7 +75,7 @@ extension Scanner {
let rules = scanner.parseRuleSet() let rules = scanner.parseRuleSet()
extension Rule { extension Rule {
func matches(rules: RuleSet, index: Int, _ s: Substring) -> Set<Substring> { func matches(rules: RuleSet, _ s: Substring) -> Set<Substring> {
switch self { switch self {
case .character(let ch): case .character(let ch):
if s.first == ch { if s.first == ch {
@ -85,28 +85,22 @@ extension Rule {
return [] return []
case let .sequence(first, second): case let .sequence(first, second):
let firstMatches = first.matches(rules: rules, index: index, s) let firstMatches = first.matches(rules: rules, s)
let result = Set(firstMatches.flatMap { x -> Set<Substring> in return Set(firstMatches.flatMap { second.matches(rules: rules, $0) })
let part = second.matches(rules: rules, index: index, x)
return part
})
return result
case let .alternative(first, second): case let .alternative(first, second):
let firstMatch = first.matches(rules: rules, index: index, s) let firstMatch = first.matches(rules: rules, s)
let secondMatch = second.matches(rules: rules, index: index, s) let secondMatch = second.matches(rules: rules, s)
let result = firstMatch.union(secondMatch) return firstMatch.union(secondMatch)
return result
case .reference(let index): case .reference(let index):
return rules[index]!.matches(rules: rules, index: index, s) return rules[index]!.matches(rules: rules, s)
} }
} }
func matches(rules: RuleSet, index: Int, _ s: String) -> Bool { func matches(rules: RuleSet, _ s: String) -> Bool {
let result = matches(rules: rules, index: index, s[...]) let result = matches(rules: rules, s[...])
return result.contains("") return result.contains("")
} }
} }
@ -135,7 +129,7 @@ let messages = scanner.readLines()
let start = Rule.reference(0) let start = Rule.reference(0)
print("part 1:", messages.lazy.filter { start.matches(rules: rules,index: 0, $0) }.count) print("part 1:", messages.lazy.filter { start.matches(rules: rules, $0) }.count)
let changedRules = """ let changedRules = """
8: 42 | 42 8 8: 42 | 42 8
@ -150,4 +144,4 @@ let ruleUpdates = changeScanner.parseRuleSet()
let newRules = rules.merging(ruleUpdates) { $1 } let newRules = rules.merging(ruleUpdates) { $1 }
print("part 2:", messages.filter { start.matches(rules: newRules, index: 0, $0) }.count) print("part 2:", messages.filter { start.matches(rules: newRules, $0) }.count)