Teaching and learning resources • Re: Advent of Code 2023

Code:

julia> include("day25.jl") # Pi Zero 700 MHzAdvent of Code 2023 Day 25 SnowverloadPart 1 The product of the two groups is 567606Total execution time 52.94287787 seconds.julia> main()Advent of Code 2023 Day 25 SnowverloadPart 1 The product of the two groups is 567606Total execution time 48.092444726 seconds.julia> main()Advent of Code 2023 Day 25 SnowverloadPart 1 The product of the two groups is 567606Total execution time 48.938123044 seconds.

Code:

#=  Advent of Code 2023 Day 25 Snowverload    Written 2024 by Eric Olson =#struct DoExit <: Exceptionendimport Base.isequal, Base.hashfunction gobble(s::String,m::String)::Tuple{String,Bool}    if length(s)<length(m)        return s,false    end    if s[1:length(m)]==m        return s[length(m)+1:end],true    end    return s,falseendfunction wskip(s::String)::String    for i=1:length(s)        if !isspace(s[i])            return s[i:end]        end    end    return ""endfunction vskip(data,i::Int)::Int    while i<=length(data)&&length(data[i])==0        i+=1    end    return iend function getalpha(s::String)::Tuple{String,String}    for i=1:length(s)        if !isletter(s[i])            return s[i:end],s[1:i-1]        end    end    return "",sendfunction getint(s::String)::Tuple{String,Int64}    n=Int64(0); ε=1    for i=1:length(s)        if s[i]=='-'            ε=-1        elseif s[i]>='0'&&s[i]<='9'            n=n*10+Int64(s[i]-'0')        else            return s[i:end],ε*n        end    end    return "",ε*nendmutable struct Edog    a::String    d::Int    f::Int    Edog(a,d)=new(a,d,0)endfunction isequal(x::Edog,y::Edog)::Bool    return x.a==y.aendfunction hash(x::Edog)::UInt    return hash(x.a)endmutable struct Wire    c::String    e::Vector{Edog}endfunction getwire(s::String)::Wire    r=s    s,c=getalpha(s)    s,f=gobble(s,": ")    if f!=true        println(r,"\nMissing component separator!")        throw(DoExit())    end    e=Vector{Edog}()    while length(s)>0        s,z=getalpha(s)        push!(e,Edog(z,0))        s=wskip(s)    end    return Wire(c,e)endmutable struct Node    w::Wire    n::Intendfunction mkpriority()::Tuple{Function,Function}    heap=Node[]    function enqueue(p::Node)        push!(heap,p)        r=length(heap)        while true            s=r÷2            if s<1 break end            if heap[s].n<=p.n break end            heap[r]=heap[s]            r=s        end        heap[r]=p    end    function dequeue()::Node        if length(heap)==0            println("Tried to remove nonexistent point!\n")            throw(DoExit())        end        t=pop!(heap)        if length(heap)==0 return t end        p=heap[1]        s0=1        while true            r0=2*s0; r1=r0+1            if r0>length(heap) break end            s1=r0            if r1<=length(heap)                if heap[r0].n>heap[r1].n                    s1=r1                end            end            if t.n<=heap[s1].n break end            heap[s0]=heap[s1]            s0=s1        end        heap[s0]=t        return p    end    return enqueue,dequeueendfunction clearflow(wire::Vector{Wire})::Nothing    for i=1:length(wire)        for e in wire[i].e            e.f=0        end    endendfunction addflow(wire::Vector{Wire},a::Int,b::Int)::Vector{Int}    K=length(wire)    enc,deq=mkpriority()    g=Vector{Int}(undef,K)    g.=typemax(Int)    g[b]=0    enc(Node(wire[b],0))    while length(enc.heap)>0        v=deq()        n=v.n+1        for e in v.w.e            if e.f>-1&&g[e.d]>n                g[e.d]=n                enc(Node(wire[e.d],n))            end        end    end    function trace()::Vector{Int}        k=a        if g[a]==typemax(Int)            return []        end        n=g[a]-1        p=[k]        for i=1:2*K            for e in wire[k].e                if e.f<1&&g[e.d]==n                    push!(p,e.d)                    e.f+=1                    for er in wire[e.d].e                        if er.d==k                            er.f-=1                            break                        end                    end                    if e.d==b                        return p                    end                    k=e.d                    n-=1                end            end        end        println("Unable to trace path from $a to $(b)!")        throw(DoExit())    end    p=trace()    return pendfunction part1(wire::Vector{Wire})::Int    K=length(wire)    a=1    g=[a]    for b=1:K        if a==b continue end        clearflow(wire)        p=addflow(wire,a,b)        p=addflow(wire,a,b)        p=addflow(wire,a,b)        p=addflow(wire,a,b)        if length(p)>0            push!(g,b)        end    end    return length(g)*(K-length(g))endfunction doinit()    data=String[]    open("day25.txt","r") do fp        data=readlines(fp)    end    wmap=Dict{String,Int}()    wire=Vector{Wire}(undef,length(data))    for i=1:length(data)        wire[i]=getwire(data[i])        wmap[wire[i].c]=i    end    function fwire(w::Vector{Edog},c::String)::Bool        for e in w            if e.a==c                return true            end        end        return false    end    for i=1:length(wire)        for e in wire[i].e            k=get(wmap,e.a,nothing)            if k==nothing                push!(wire,Wire(e.a,Vector{Edog}()))                k=length(wire)                wmap[wire[k].c]=k            end            if !fwire(wire[k].e,wire[i].c)                push!(wire[k].e,Edog(wire[i].c,0))            end        end    end    for i=1:length(wire)        for e in wire[i].e            e.d=wmap[e.a]        end    end    p1=part1(wire)    println("Part 1 The product of the two groups is ",p1)endfunction main()::Nothing    t=@elapsed try        println("Advent of Code 2023 Day 25 Snowverload\n")        doinit()        throw(DoExit())    catch r        if !isa(r,DoExit)            rethrow(r)        end    end    println("\nTotal execution time ",t," seconds.")end main()