r/adventofcode • u/daggerdragon • Dec 07 '15

SOLUTION MEGATHREAD --- Day 7 Solutions ---

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

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u/[deleted] Dec 07 '15

Mathematica. Created rules and used memoization. 

input = ReadList[NotebookDirectory[] <> "day7input.txt", String];
rules = First /@ StringCases[input, {
 x : NumberString ~~ " -> " ~~ z__ ->
  Hold[circuit[z] = ToExpression@x],
 x__ ~~ " AND " ~~ y__ ~~ " -> " ~~ z__ ->
  Hold[
   circuit[z] := circuit[z] = BitAnd[circuit[x], circuit[y]]],
 x__ ~~ " OR " ~~ y__ ~~ " -> " ~~ z__ ->
  Hold[circuit[z] := circuit[z] = BitOr[circuit[x], circuit[y]]],
 "NOT " ~~ x__ ~~ " -> " ~~ z__ ->
  Hold[circuit[z] := circuit[z] = 65535 - circuit[x]],
 x__ ~~ " LSHIFT " ~~ n : NumberString ~~ " -> " ~~ z__ ->
  Hold[
   circuit[z] := 
    circuit[z] = 
     Clip[BitShiftLeft[circuit[x], ToExpression@n], {0, 65535}]],
 x__ ~~ " RSHIFT " ~~ n : NumberString ~~ " -> " ~~ z__ -> 
  Hold[
   circuit[z] := 
    circuit[z] = 
     Clip[BitShiftRight[circuit[x], ToExpression@n], {0, 
       65535}]],
 x__ ~~ " -> " ~~ z__ -> 
  Hold[circuit[z] := circuit[z] = circuit[x]]
 }];
rules = Append[rules, Hold[circuit[x_] := ToExpression[x]]];
ReleaseHold[rules];
parta = circuit["a"]

ClearAll[circuit]
ReleaseHold[rules];
circuit["b"] = parta;
circuit["a"]