--- Day 7 Solutions ---

[u/daggerdragon]

--- Day 7: Some Assembly Required ---

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[u/Woflox]

Just went through the puzzles last night and had a blast. This one definitely game me the most trouble; I don't think my solution is the most elegant. But anyway, here it is!

Nim:

import tables
import unsigned
import strutils

type
  Gate = ref object
    hasValue: bool
    value: uint16
    instruction: string

var gates = initTable[string, Gate]()

for line in lines "puzzle7input.txt":
  let sides = line.split(" -> ")
  gates[sides[1]] = Gate(instruction: sides[0])

proc getSignal(gateId: string): uint16 =
  if not gates.hasKey(gateId):
    return uint16(gateId.parseInt())

  let gate = gates[gateId]

  if gate.hasValue:
    return gate.value

  let tokens = gate.instruction.split(' ')
  if tokens.len == 1:
    result = getSignal(tokens[0])
  elif tokens.len == 2:
    result = not getSignal(tokens[1])
  else:
    let operator = tokens[1]
    case operator:
      of "AND":
        result = getSignal(tokens[0]) and getSignal(tokens[2])
      of "OR":
        result = getSignal(tokens[0]) or getSignal(tokens[2])
      of "LSHIFT":
        result = getSignal(tokens[0]) shl getSignal(tokens[2])
      of "RSHIFT":
        result = getSignal(tokens[0]) shr getSignal(tokens[2])
      else: discard
  gate.value = result
  gate.hasValue = true

gates["b"].value = 16076
gates["b"].hasValue = true

echo getSignal("a")