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+import os, argparse, re
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+
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+def solve_task(lines):
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+ # Extract the initial stacks and instructions from the input
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+ (stacks, raw_instructions) = load_stacks(lines)
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+
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+ #print(f"Stacks: {stacks}\n")
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+ #print(f"Instructions: {raw_instructions}")
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+ #display_stacks(stacks)
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+
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+ # Parse the instructions into a list of tuples
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+ packed_instructions = pack_instructions(raw_instructions)
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+ #print(f"Packed: {packed_instructions}")
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+
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+ # Perform all instructions
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+ for instruction in packed_instructions:
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+ perform_instruction(stacks, instruction)
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+ #display_stacks(stacks)
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+
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+ # Get the answer by getting the uppermost (last) element of
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+ # each stack. This way has side effects, but we won't need
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+ # to preserve the stacks past this line.
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+ answer = []
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+ for s in stacks:
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+ if len(s) != 0:
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+ answer.append(s[-1])
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+ print("Final answer: " + ''.join(answer))
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+
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+def display_stacks(stacks):
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+ print("Current stacks:")
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+ for stack in stacks:
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+ print(''.join(stack))
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+
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+def perform_instruction(stacks, instruction):
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+ quantity = int(instruction[0])
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+ source = int(instruction[1]) - 1
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+ destination = int(instruction[2]) - 1
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+
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+ # Since lists are mutable, we can manipulate the supplied lists
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+ # instead of returning new ones
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+ stacks[destination].extend(stacks[source][-quantity:])
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+ del stacks[source][-quantity:]
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+
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+def pack_instructions(instr):
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+ # Return a list of instruction-tuples
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+ return [get_instruction_tuple(i) for i in instr]
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+
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+def get_instruction_tuple(intr_line):
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+ # Returns a tuple with three values (quantity, source, destination)
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+ m = re.match("move (\d+) from (\d+) to (\d+)", intr_line)
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+ return (m.group(1), m.group(2), m.group(3))
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+
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+def load_stacks(lines):
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+ number_of_piles = (len(lines[0])+1)//4
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+ piles = [[] for x in range(number_of_piles)]
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+ instructions_start_line = 0
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+ for linum in range(len(lines)):
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+ line = lines[linum]
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+ for col in range(len(line)):
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+ c = line[col]
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+ if col % 4 != 1 or c == ' ':
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+ continue
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+ if c == '1':
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+ instructions_start_line = linum+2
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+ break
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+ pile = col // 4
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+ piles[pile].insert(0, c)
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+
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+ if instructions_start_line != 0:
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+ break
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+ return (piles, lines[instructions_start_line:])
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+
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+
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+def read_lines(filename):
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+ lines = []
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+ with open(filename) as infile:
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+ for raw_line in infile:
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+ line = raw_line.replace('\n', '')
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+ line = line.replace('\r', '')
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+ #line = raw_line.rstrip() # Usefull to keep space in this task
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+ lines.append(line)
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+ return lines
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+
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+def parse_arguments():
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+ parser = argparse.ArgumentParser(description="Script that solves the case",epilog="Have a nice day!")
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+ parser.add_argument('filename', nargs='?', default="example.txt", help='Input file')
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+ args = parser.parse_args()
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+ return args
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+
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+def main():
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+ args = parse_arguments()
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+ lines = read_lines(args.filename)
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+ solve_task(lines)
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+
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+if __name__ == "__main__":
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+ main()
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