commit 8671154520894dc75e1ac90a9066f53c256cf477 · drubery.com/aoc2025

+78
src/Day10_part2.py
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       import sys

     

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       import itertools

     

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       def parseIntList(s):

     

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           return list(map(int, s[1:-1].split(",")))

     

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       def parseMachine(line):

     

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           words = line.split(" ")

     

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           buttons = list(map(parseIntList, words[1:-1]))

     

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           goal = parseIntList(words[-1])

     

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           return (buttons, goal)

     

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       def solveMachine(machine):

     

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           (buttons, goal) = machine

     

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           rows = len(goal)

     

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           cols = len(buttons) + 1

     

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           matrix = [[0 for _ in range(rows)] for _ in range(cols)]

     

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           for i,button in enumerate(buttons):

     

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               for b in button:

     

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                   matrix[i][b] = 1

     

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           for i in range(rows):

     

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               matrix[cols-1][i] = -goal[i]

     

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           maxPresses = max(goal)

     

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           # Row reduce matrix

     

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           curRow,curCol = 0,0

     

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           freeVars = []

     

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           while curRow < rows and curCol < cols:

     

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               pivotRow = None

     

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               for i in range(curRow, rows):

     

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                   if matrix[curCol][i] != 0:

     

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                       pivotRow = i

     

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                       break

     

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               if pivotRow is None:

     

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                   freeVars.append(curCol)

     

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                   curCol += 1

     

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                   continue

     

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               for i in range(cols):

     

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                   matrix[i][curRow], matrix[i][pivotRow] = matrix[i][pivotRow], matrix[i][curRow]

     

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               for j in range(rows):

     

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                   if j == curRow:

     

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                       continue

     

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                   a,b = matrix[curCol][curRow],-matrix[curCol][j]

     

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                   for i in range(cols):

     

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                       matrix[i][j] = a*matrix[i][j] + b*matrix[i][curRow]

     

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               curRow += 1

     

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               curCol += 1

     

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           while curCol < cols:

     

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               freeVars.append(curCol)

     

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               curCol += 1

     

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           # The last col is going to be fixed at 1

     

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           freeVars.pop()

     

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           minMoves = maxPresses * len(buttons)

     

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           for freeAssignment in itertools.product(range(maxPresses+1), repeat=len(freeVars)):

     

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               varAssignment = [None for i in range(cols)]

     

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               varAssignment[-1] = 1

     

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               valid = True

     

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               for i,v in enumerate(freeVars):

     

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                   varAssignment[v] = freeAssignment[i]

     

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               for j in range(rows-1,-1,-1):

     

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                   nonZeroCols = [i for i in range(cols) if matrix[i][j] != 0]

     

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                   if len(nonZeroCols) == 0:

     

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                       continue

     

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                   rhs = -sum([varAssignment[c]*matrix[c][j] for c in nonZeroCols[1:]])

     

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                   lhs = matrix[nonZeroCols[0]][j]

     

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                   if rhs % lhs != 0:

     

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                       valid = False

     

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                       break

     

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                   if rhs // lhs < 0:

     

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                       valid = False

     

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                       break

     

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                   varAssignment[nonZeroCols[0]] = rhs // lhs

     

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               if not valid:

     

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                   continue

     

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               minMoves = min(minMoves, sum(varAssignment) - 1)

     

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           return minMoves

     

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       machines = [parseMachine(line) for line in open(sys.argv[1]).read().strip().split("\n")]

     

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       print(sum(map(solveMachine, machines)))