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import strutils
import strformat
import algorithm
type
Data = ref object
val: int
list: seq[Data]
Packet = tuple
first: Data
second: Data
Input = seq[Packet]
proc `$`(data: Data): string =
if data.val != -1:
return fmt"{data.val}"
result = "[" & data.list.join(",") & "]"
proc parseData(strData: string, i: var int): Data =
result = Data(val: -1, list: newSeq[Data]())
let dataLen = strData.len()
while i < dataLen:
case strData[i]:
of '[':
i += 1
result.list.add(parseData(strData, i))
of ']':
i += 1
return result
of ',':
i += 1
else:
var j = i
while j < dataLen and strData[j].isDigit():
j += 1;
let toPush = Data(val: strData[i..<j].parseInt())
result.list.add(toPush)
i = j
proc parsePacket(strPacket: string): Packet =
let strDatas = strPacket.splitLines()
assert(strDatas.len() == 2)
var
i0 = 0
i1 = 0
result = (parseData(strDatas[0][1..^2], i0), parseData(strDatas[1][1..^2], i1))
proc parseFile(content: string): Input =
let strPackets = content.strip().split("\n\n")
for strPacket in strPackets:
result.add(parsePacket(strPacket))
proc compare(A, B: int): int =
if A < B: return -1
elif A > B: return 1
else: return 0
proc dataListForm(data: Data): Data =
# Check if its already in list form
if data.val == -1:
return data
result = Data(val: -1, list: @[data])
proc compare(A, B: Data): int =
# Both numbers:
if A.val != -1 and B.val != -1:
return compare(A.val, B.val)
# Transform both data to list form
let
A = dataListForm(A)
B = dataListForm(B)
assert(A.val == -1 and B.val == -1)
# Both are lists now
let
li = A.list.len()
lj = B.list.len()
N = min(li, lj)
var i = 0
while i < N:
let res = compare(A.list[i], B.list[i])
if res != 0:
return res
i += 1
return compare(li, lj)
proc part1(Packets: Input): int =
for i, packet in Packets:
# echo fmt"Checking packet {packet}"
let comparison = compare(packet.first, packet.second)
# echo fmt"result = {comparison}"
if comparison < 0:
result += i+1
proc part2(Packets: Input): int =
let driverPackets = parseFile("[[6]]\n[[2]]\n")
let first = driverPackets[0].first
let second = driverPackets[0].second
var datas = @[first, second]
for packet in Packets:
datas.add(packet.first)
datas.add(packet.second)
datas.sort(compare)
let firstIndex = datas.binarySearch(first, compare) + 1
let secondIndex = datas.binarySearch(second, compare) + 1
return firstIndex * secondIndex
let content = readFile("./input.txt")
let input = parseFile(content)
echo part1(input)
echo part2(input)
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