Teaching and learning resources • Re: Advent of Code 2023

Code:

julia> include("day17.jl") # Pi Zero 700 MHzAdvent of Code 2023 Day 17 Clumsy CruciblePart 1 The least heat loss is 1004Part 2 Ultra crucible heat loss is 1171Total execution time 54.888552316 seconds.julia> main()Advent of Code 2023 Day 17 Clumsy CruciblePart 1 The least heat loss is 1004Part 2 Ultra crucible heat loss is 1171Total execution time 56.025290804 seconds.julia> main()Advent of Code 2023 Day 17 Clumsy CruciblePart 1 The least heat loss is 1004Part 2 Ultra crucible heat loss is 1171Total execution time 56.283473324 seconds.

Code:

#=  Advent of Code 2023 Day 17 Clumsy Crucible    Written 2024 by Eric Olson =#struct DoExit <: Exceptionendmutable struct Node    p::Vector{Int}    d::Int    h::Intendfunction mkpriority()    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].h<=p.h 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].h>heap[r1].h                    s1=r1                end            end            if t.h<=heap[s1].h break end            heap[s0]=heap[s1]            s0=s1        end        heap[s0]=t        return p    end    return enqueue,dequeueend@isdefined(dirs) || const dirs=[[0,1],[-1,0],[0,-1],[1,0]]function part1(data::Vector{String})::Int    M=length(data)    N=length(data[1])    function inbound(p::Vector{Int})::Bool        if p[1]<1||p[1]>M return false end        if p[2]<1||p[2]>N return false end        return true    end    H=[parse(Int,data[i][j]) for i=1:M,j=1:N]    W=[[typemax(Int),typemax(Int)] for i=1:M,j=1:N]    enq,deq=mkpriority()    enq(Node([1,1],1,0)); enq(Node([1,1],4,0))    W[1,1]=[0,0]    while length(enq.heap)>0        v=deq()        p=copy(v.p)        h=v.h        for i=1:3            p+=dirs[v.d]            if inbound(p)                h+=H[p...]                d=v.d%4+1                if h<W[p...][d%2+1]                    W[p...][d%2+1]=h                    enq(Node(p,d,h))                    d=(d+1)%4+1                    enq(Node(p,d,h))                end            end        end    end    return minimum(W[M,N])endfunction part2(data::Vector{String})::Int    M=length(data)    N=length(data[1])    function inbound(p::Vector{Int})::Bool        if p[1]<1||p[1]>M return false end        if p[2]<1||p[2]>N return false end        return true    end    H=[parse(Int,data[i][j]) for i=1:M,j=1:N]    W=[[typemax(Int),typemax(Int)] for i=1:M,j=1:N]    enq,deq=mkpriority()    enq(Node([1,1],1,0)); enq(Node([1,1],4,0))    W[1,1]=[0,0]    while length(enq.heap)>0        v=deq()        p=copy(v.p)        h=v.h        for i=1:10            p+=dirs[v.d]            if inbound(p)                h+=H[p...]                if i>=4                    d=v.d%4+1                    if h<W[p...][d%2+1]                        W[p...][d%2+1]=h                        enq(Node(p,d,h))                        d=(d+1)%4+1                        enq(Node(p,d,h))                    end                end            end        end    end    return minimum(W[M,N])endfunction doinit()    data=[]    open("day17.txt","r") do fp        data=readlines(fp)    end    p1=part1(data)    p2=part2(data)    println("Part 1 The least heat loss is ",p1)    println("Part 2 Ultra crucible heat loss is ",p2)endfunction main()    t=@elapsed try        println("Advent of Code 2023 Day 17 Clumsy Crucible\n")        doinit()        throw(DoExit())    catch r        if !isa(r,DoExit)            rethrow(r)        end    end    println("\nTotal execution time ",t," seconds.")end main()