Advent of Code 2022 - Day 5
Challenge
— Day 5: Supply Stacks —
The expedition can depart as soon as the final supplies have been unloaded from the ships. Supplies are stored in stacks of marked crates, but because the needed supplies are buried under many other crates, the crates need to be rearranged.
The ship has a giant cargo crane capable of moving crates between stacks. To ensure none of the crates get crushed or fall over, the crane operator will rearrange them in a series of carefully-planned steps. After the crates are rearranged, the desired crates will be at the top of each stack.
The Elves don’t want to interrupt the crane operator during this delicate procedure, but they forgot to ask her which crate will end up where, and they want to be ready to unload them as soon as possible, so they can embark.
They do, however, have a drawing of the starting stacks of crates and the rearrangement procedure (your puzzle input). or example:
[D]
[N] [C]
[Z] [M] [P]
1 2 3
move 1 from 2 to 1
move 3 from 1 to 3
move 2 from 2 to 1
move 1 from 1 to 2In this example, there are three stacks of crates. Stack 1
contains two crates: crate Z is on the bottom, and
crate N is on top. Stack 2 contains three crates; from
bottom to top, they are crates M, C, and
D. Finally, stack 3 contains a single crate,
P.
Then, the rearrangement procedure is given. In each step of the procedure, a quantity of crates is moved from one stack to a different stack. In the first step of the above rearrangement procedure, one crate is moved from stack 2 to stack 1, resulting in this configuration:
[D]
[N] [C]
[Z] [M] [P]
1 2 3In the second step, three crates are moved from stack 1 to stack 3. Crates are moved one at a time, so the first crate to be moved (D) ends up below the second and third crates:
[Z]
[N]
[C] [D]
[M] [P]
1 2 3Then, both crates are moved from stack 2 to stack 1. Again,
because crates are moved one at a time, crate
C ends up below crate M:
[Z]
[N]
[M] [D]
[C] [P]
1 2 3Finally, one crate is moved from stack 1 to stack 2:
[Z]
[N]
[D]
[C] [M] [P]
1 2 3The Elves just need to know which crate will end up on
top of each stack; in this example, the top crates are
C in stack 1, M in stack 2, and Z in stack
3, so you should combine these together and give the Elves the
message CMZ.
After the rearrangement procedure completes, what crate ends up on top of each stack?
Your puzzle answer was TGWSMRBPN.
— Part Two —
As you watch the crane operator expertly rearrange the crates, you notice the process isn’t following your prediction.
Some mud was covering the writing on the side of the crane, and you quickly wipe it away. The crane isn’t a CrateMover 9000 - it’s a CrateMover 9001.
The CrateMover 9001 is notable for many new and exciting features: air conditioning, leather seats, an extra cup holder, and the ability to pick up and move multiple crates at once.
Again considering the example above, the crates begin in the same configuration:
[D] [N] [C] [Z] [M] [P] 1 2 3
Moving a single crate from stack 2 to stack 1 behaves the same as before:
[D] [N] [C] [Z] [M] [P] 1 2 3
However, the action of moving three crates from stack 1 to stack 3 means that those three moved crates stay in the same order, resulting in this new configuration:
[D] [N] [C] [Z] [M] [P] 1 2 3
Next, as both crates are moved from stack 2 to stack 1, they retain their order as well:
[D] [N] [C] [Z] [M] [P] 1 2 3
Finally, a single crate is still moved from stack 1 to stack 2, but now it’s crate C that gets moved:
[D] [N] [Z] [M] [C] [P] 1 2 3
In this example, the CrateMover 9001 has put the
crates in a totally different order:
MCD.
Before the rearrangement process finishes, update your simulation so that the Elves know where they should stand to be ready to unload the final supplies. After the rearrangement procedure completes, what crate ends up on top of each stack?
Your puzzle answer was TZLTLWRNF.
Solution
This solution is written in visual basic
' Solution for Advent of Code 2022 day 5.
' I did not really like visual basic, this code is not beautiful, so go easy on me
Imports System.IO
Imports Microsoft.VisualBasic.FileIO
Module Program
Sub Main(args As String())
Dim reader as StreamReader = FileSystem.OpenTextFileReader("../../../input.txt")
Dim row as String
' Use stack data structure for saving stack information
Dim stacks = New ArrayList(10)
Dim helpStacks = New ArrayList(10)
For i = 0 To 9
stacks.Add(New Stack)
helpStacks.Add(New Stack)
Next
Dim initialized = False
Do
' Read line
row = reader.ReadLine()
If Not initialized Then
' not initialized
Dim index As Int16 = 0
Dim stackNumber = 0
For Each ch As Char in row
if (index - 1) Mod 4 = 0 Then
if Char.IsDigit(ch) Then
initialized = True
' Add help stacks to stacks
For i = 0 To stacks.Count-1
Dim helpStack As Stack = helpStacks.Item(i)
Dim stack As Stack = stacks.Item(i)
While helpStack.Count > 0
stack.Push(helpStack.Peek())
helpStack.Pop()
End While
stacks.Item(i) = stack
helpStacks.Item(i) = helpStacks
Next
' Print Stack structure
' For i = 0 To 9
' Dim stack As Stack = stacks.Item(i)
' While stack.Count > 0
' Console.Write(stack.Pop())
' End While
' Console.WriteLine()
' Next
Exit For
End If
stackNumber += 1
if not ch = " " Then
Dim stack As Stack = helpStacks.Item(stackNumber)
stack.Push(ch)
helpStacks.Item(stackNumber) = stack
End If
End If
index += 1
Next
Else If not String.IsNullOrEmpty(row) Then
' Read Instructions
row = row.Replace("move ", "")
row = row.Replace(" from ", " ")
row = row.Replace(" to ", " ")
row = row.Replace("\n", "")
Dim amount = 0
Dim src = 0
Dim dst = 0
' Put Instructions to variables
Dim data = row.Split()
For Each num in data
if not num = "" Then
if amount = 0 Then
amount = num
Else If src = 0 Then
src = num
Else
dst = num
End If
End If
Next
' !! Comment part 1 or 2 out to get proper answer !!
' Part 1 Beginning
for i = 1 To amount
Dim srcStack = stacks.Item(src)
Dim dstStack = stacks.Item(dst)
if srcStack.Count Then
dstStack.Push(srcStack.Pop())
End If
Next
' Part 1 End
' Part 2 Beginning
Dim helpStack = new Stack
for i = 1 To amount
Dim srcStack = stacks.Item(src)
if srcStack.Count Then
helpStack.Push(srcStack.Pop())
End If
Next
While helpStack.Count > 0
stacks.Item(dst).Push(helpStack.Pop())
End While
' Part 2 End
End If
Loop Until row Is Nothing
Console.Write("Answer: ")
For i = 1 To stacks.Count-1
Dim stack As Stack = stacks.Item(i)
if stack.Count > 0 Then
Console.Write(stack.Peek())
End If
Next
End Sub
End Module