Teaching and learning resources • Re: Advent of Code 2023

Code:

julia> include("day22.jl") # Pi Zero 700 MHzAdvent of Code 2023 Day 22 Sand SlabsPart 1 There are 459 safe bricksPart 2 There are 75784 bricks that fallTotal execution time 19.680736116 seconds.julia> main()Advent of Code 2023 Day 22 Sand SlabsPart 1 There are 459 safe bricksPart 2 There are 75784 bricks that fallTotal execution time 5.751008091 seconds.julia> main()Advent of Code 2023 Day 22 Sand SlabsPart 1 There are 459 safe bricksPart 2 There are 75784 bricks that fallTotal execution time 5.67593156 seconds.

Code:

#=  Advent of Code 2023 Day 22 Sand Slabs    Written 2024 by Eric Olson =#struct DoExit <: Exceptionendfunction 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)    for i=1:length(s)        if s[i]>='0'&&s[i]<='9'            n=n*10+Int64(s[i]-'0')        else            return s[i:end],n        end    end    return "",nendmutable struct Point    x::Int    y::Int    z::Intendmutable struct Block    a::Point    b::Point    u::Set{Int}    d::Set{Int}    Block(a,b)=new(a,b,Set{Int}(),Set{Int}())endfunction getblock(s::String)::Block    r=s    s,ax=getint(s); ax+=1    if begin s,f=gobble(s,","); !f end        println(r,"\nCan't find comma after a.x coordinate!")        throw(DoExit())    end    s,ay=getint(s); ay+=1    if begin s,f=gobble(s,","); !f end        println(r,"\nCan't find comma after a.y coordinate!")        throw(DoExit())    end    s,az=getint(s)    if begin s,f=gobble(s,"~"); !f end        println(r,"\nCan't find tilde after a.z coordinate!")        throw(DoExit())    end    s,bx=getint(s); bx+=1    if begin s,f=gobble(s,","); !f end        println(r,"\nCan't find comma after b.x coordinate!")        throw(DoExit())    end    s,by=getint(s); by+=1    if begin s,f=gobble(s,","); !f end        println(r,"\nCan't find comma after b.y coordinate!")        throw(DoExit())    end    s,bz=getint(s)    if length(s)>0        println(r,"\nCharacters after at end of location!")        throw(DoExit())            end    return Block(Point(ax,ay,az),Point(bx,by,bz))endmutable struct Visible    k::Int    z::Intendfunction drop(topo::Matrix{Visible},block::Block,b::Int)::Bool    dx=block.b.x-block.a.x    dy=block.b.y-block.a.y    dz=block.b.z-block.a.z    imax=abs(dx)    if imax<abs(dy) imax=abs(dy) end    if imax<abs(dz) imax=abs(dz) end    f=false    for i=0:imax        x=block.a.x+i*sign(dx)        y=block.a.y+i*sign(dy)        z=block.a.z+i*sign(dz)        if topo[x,y].z>=z-1            f=true            push!(block.d,topo[x,y].k)        end    end    if f        for i=0:imax            x=block.a.x+i*sign(dx)            y=block.a.y+i*sign(dy)            z=block.a.z+i*sign(dz)            topo[x,y].k=b            if topo[x,y].z<z                 topo[x,y].z=z            end        end    end    return fendfunction part1(blocks::Vector{Block})::Int64    K=length(blocks)    disint=ones(Bool,K)    for k=2:K        if length(blocks[k].d)==1            for i in blocks[k].d                disint[i]=false            end        end    end    return sum(disint)endfunction part2(blocks::Vector{Block})::Int64    K=length(blocks)    function poof(k::Int,disint::Set{Int})::Int        push!(disint,k)        r=1        for i in blocks[k].u            d=setdiff(blocks[i].d,disint)            if length(d)==0                r+=poof(i,disint)            end        end        return r    end    s=0    for k=2:K        s+=poof(k,Set{Int}())-1    end    return sendfunction doinit()    data=String[]    open("day22.txt","r") do fp        data=readlines(fp)    end    M=0; N=0; K=length(data)+1    blocks=Vector{Block}(undef,K)    blocks[1]=Block(Point(1,1,0),Point(0,0,0))    for k=2:K        s=data[k-1]        r=getblock(s)        if M<r.a.x M=r.a.x end        if N<r.a.y N=r.a.y end        if M<r.b.x M=r.b.x end        if N<r.b.y N=r.b.y end        blocks[k]=r    end    blocks[1].b.x=M; blocks[1].b.y=N    P=sortperm([blocks[k].a.z for k=1:K])    blocks=blocks[P]    topo=Matrix{Visible}(undef,M,N)    for j=1:N        for i=1:M            topo[i,j]=Visible(1,0)        end    end    for k=2:K        while !drop(topo,blocks[k],k)            blocks[k].a.z-=1            blocks[k].b.z-=1        end        for i in blocks[k].d            push!(blocks[i].u,k)        end    end    p1=part1(blocks)    p2=part2(blocks)    println("Part 1 There are ",p1," safe bricks")    println("Part 2 There are ",p2," bricks that fall")endfunction main()    t=@elapsed try        println("Advent of Code 2023 Day 22 Sand Slabs\n")        doinit()        throw(DoExit())    catch r        if !isa(r,DoExit)            rethrow(r)        end    end    println("\nTotal execution time ",t," seconds.")end main()