Day Fourteen, Part II (2020)

1 files changed, 37 insertions, 8 deletions

diff --git a/2020/fourteen.nim b/2020/fourteen.nim
index e333cf9..3d6741d 100644
--- a/2020/fourteen.nim
+++ b/2020/fourteen.nim
@@ -1,21 +1,50 @@
 # Day Fourteen: Docking Data
-import os, strutils, sequtils
+import std/[os, strutils, sequtils, sugar, tables]
 
 let input: string = paramStr(1)
-let program: seq[tuple[address, value: string]] = map(split(strip(readFile(input)), '\n'),
-  func (param: string): (string, string) =
-    (split(param, " = ")[0], split(param, " = ")[1]))
+let program: seq[tuple[address, value: string]] =
+  input.readFile().strip().split('\n')
+  .map(param => (param.split(" = ")[0], param.split(" = ")[1]))
 
-var mask: string = repeat('X', 36)
+var mask: string = 'X'.repeat(36)
 var memory: seq[int] = newSeq[int](99999)
 for line in program:
   if line.address == "mask":
     mask = line.value
   elif line.address[0..2] == "mem":
-    var value: string = toBin(parseInt(line.value), 36)
+    var value: string = line.value.parseInt.toBin(36)
     for i, bit in mask:
       if bit != 'X':
         value[i] = bit
-    memory[parseInt(line.address[4..^2])] = fromBin[int](value)
+    memory[line.address[4..^2].parseInt()] = fromBin[int](value)
 
-echo foldl(memory, a + b)
+echo memory.foldl(a + b)
+
+func genadds(addresses: seq[string]): seq[string] =
+  for address in addresses:
+    for i, c in address:
+      if c == 'X':
+        result.add(address[0..(i-1)] & '0' & address[(i+1)..^1])
+        result.add(address[0..(i-1)] & '1' & address[(i+1)..^1])
+        break
+    if result.len == 0:
+      return addresses
+  return genadds(result)
+
+mask = 'X'.repeat(36)
+var memorii = initTable[int, int]()
+for line in program:
+  if line.address == "mask":
+    mask = line.value
+  elif line.address[0..2] == "mem":
+    var address = line.address[4..^2].parseInt().toBin(36)
+    var value = line.value.parseInt.toBin(36)
+    for i, bit in mask:
+      if bit == '1':
+        address[i] = '1'
+      elif bit == 'X':
+        address[i] = 'X'
+    for address in genadds(@[address]):
+      memorii[fromBin[int](address)] = fromBin[int](value)
+
+echo memorii.values.toSeq.foldl(a + b)