[2023] Day19

Author: lambda-mike

.github/workflows/2023-julia.yaml

@@ -28,4 +28,5 @@ jobs:
         julia day08.jl
         julia day09.jl
         julia day15.jl
+        julia day19.jl
 

2023/day19.jl

@@ -0,0 +1,221 @@
+@enum Rating X M A S
+
+@enum Op LT GT
+
+struct Part
+    x::Int
+    m::Int
+    a::Int
+    s::Int
+end
+
+abstract type Target end
+struct TargetWorkflow <: Target
+    name::String
+end
+struct TargetAccepted <: Target end
+struct TargetRejected <: Target end
+
+abstract type Rule end
+struct Rule3 <: Rule
+    rating::Rating
+    op::Op
+    num::Int
+    target::Target
+end
+struct Rule1 <: Rule
+    target::Target
+end
+
+struct Workflow
+    name::String
+    rules::Vector{Rule}
+end
+
+function parseTarget(s::AbstractString)::Target
+    if s == "A" return TargetAccepted()
+    elseif s == "R" return TargetRejected()
+    else TargetWorkflow(s)
+    end
+end
+
+function parseOp(op::Char)::Op
+    return op == '<' ? LT : GT
+end
+
+function parseRating(s::AbstractString)::Rating
+    if s == "x" return X
+    elseif s == "m" return M
+    elseif s == "a" return A
+    else return S
+    end
+end
+
+function parseRule(str::AbstractString)::Rule
+    tokens = split(str, [ '<', '>', ':' ])
+    if length(tokens) == 1
+        return Rule1(parseTarget(tokens[1]))
+    else
+        rating = parseRating(tokens[1])
+        op = parseOp(str[length(tokens[1]) + 1])
+        num = parse(Int, tokens[2])
+        target = parseTarget(tokens[3])
+        return Rule3(rating, op, num, target)
+    end
+end
+
+function parseInput(input)::Tuple{Vector{Workflow}, Vector{Part}}
+    partsStartIndex = 0
+    workflows = Workflow[]
+    parts = Part[]
+    for (i, line) in enumerate(input)
+        if length(line) == 0 partsStartIndex = i + 1; break end
+        rulesSectionIndex = findfirst('{', line)
+        name = line[1:rulesSectionIndex-1]
+        rulesSection = line[rulesSectionIndex+1:end-1]
+        rules = Rule[]
+        for r in split(rulesSection, ",")
+            rule = parseRule(r)
+            push!(rules, rule)
+        end
+        push!(workflows, Workflow(name, rules))
+    end
+    for pStr in input[partsStartIndex:end]
+        tokens = split(pStr, [ '{', '}', ',' ])
+        x = parse(Int, tokens[2][3:end])
+        m = parse(Int, tokens[3][3:end])
+        a = parse(Int, tokens[4][3:end])
+        s = parse(Int, tokens[5][3:end])
+        part = Part(x, m, a, s)
+        push!(parts, part)
+    end
+    (workflows, parts)
+end
+
+function getPartRating(part::Part, rating::Rating)::Int
+    if rating == X return part.x
+    elseif rating == M return part.m
+    elseif rating == A return part.a
+    else return part.s
+    end
+end
+
+function sendToWorkflow(workflowsDict::Dict{String, Workflow}, name::String, part::Part)::Union{TargetAccepted, TargetRejected}
+    result::Target = TargetWorkflow(name)
+    while result != TargetRejected() && result !== TargetAccepted()
+        workflow = workflowsDict[result.name]
+        for r in workflow.rules
+            if r isa Rule1
+                result = r.target
+            else
+                rating = getPartRating(part, r.rating)
+                if r.op == LT
+                    rating >= r.num && continue
+                else
+                    rating <= r.num && continue
+                end
+                result = r.target
+            end
+            break
+        end
+    end
+    return result
+end
+
+function solveA(input)
+    workflows, parts = parseInput(input)
+    workflowsDict::Dict{String, Workflow} = map(x -> (x.name, x), workflows) |> Dict
+    return [ sum([ p.x, p.m, p.a, p.s ]) for p in parts if TargetAccepted() == sendToWorkflow(workflowsDict, "in", p) ] |> x -> sum(x; init = 0)
+end
+
+function mergeRule(rule::Rule3, rng::Tuple{Int, Int})::Tuple{Int, Int}
+    a, b = rng
+    if rule.op == LT
+        rule.num > b && return rng
+        rule.num in a:b && return (a, rule.num - 1)
+        pritnln("mergeRule WRN $rule ($a - $b)")
+        return (0, 0)
+    else
+        rule.num < a && return rng
+        rule.num in a:b && return (rule.num + 1, b)
+        pritnln("mergeRule WRN $rule ($a - $b)")
+        return (0, 0)
+    end
+end
+
+function mergeRules(acc, rule::Rule3)
+    if rule.rating == X return (; acc..., x = mergeRule(rule, acc.x))
+    elseif rule.rating == M return (; acc..., m = mergeRule(rule, acc.m))
+    elseif rule.rating == A return (; acc..., a = mergeRule(rule, acc.a))
+    else return (; acc..., s = mergeRule(rule, acc.s))
+    end
+end
+
+function reverseRule(rule::Rule3)::Rule3
+    if rule.op == LT
+        Rule3(rule.rating, GT, rule.num - 1, rule.target)
+    else
+        Rule3(rule.rating, LT, rule.num + 1, rule.target)
+    end
+end
+
+function solveB(input)
+    workflows, _ = parseInput(input)
+    dict::Dict{String, Workflow} = map(x -> (x.name, x), workflows) |> Dict
+    # vector of workflow names
+    queue = Tuple{String, Vector{Rule}}[ ("in", []) ]
+    results = Vector{Rule3}[]
+    while length(queue) > 0
+        name, sourceRules = pop!(queue)
+        # copy of rules accumulated from previous workflows
+        rules = copy(sourceRules)
+        # all rules accumulated for this workflow
+        # next rules are added to previous rules which should already be reversed (LT <-> GT)
+        prevRules = Rule3[]
+        for r in dict[name].rules
+            newRules = [ rules..., prevRules... ]
+            if r.target isa TargetAccepted
+                if r isa Rule3
+                    push!(newRules, r)
+                end
+                push!(results, newRules)
+            end
+            if r.target isa TargetWorkflow
+                if r isa Rule3
+                    push!(newRules, r)
+                end
+                push!(queue, (r.target.name, newRules))
+            end
+            r isa Rule3 && push!(prevRules, reverseRule(r))
+        end
+    end
+    combinations = 0
+    limit = 4000
+    for rules in results
+        (; x, m, a, s) = reduce((acc, a) -> mergeRules(acc, a), rules; init = (x = (1, limit), m = (1, limit), a = (1, limit), s = (1, limit)))
+        combinations += prod([ z[2] - z[1] + 1 for z in [ x, m, a ,s ]])
+    end
+    combinations
+end
+
+function main(file = "day19.txt")
+    input = collect(eachline(file))
+    # input = strip(read(file, String))
+    # 446935
+    println("Solving Day19A...")
+    println(solveA(input))
+    # 141882534122898
+    println("Solving Day19B...")
+    println(solveB(input))
+end
+
+if !isinteractive()
+    main("day19s.txt")
+end
+
+function repl()
+    # file = "day19s.txt"
+    file = "day19.txt"
+    println("file: $file")
+    main(file)
+end