En Python

Ce qui est assez casse-pied dans ce problème, c'est que les données d'entrées sont dans un ordre qui est optimisé pour la lecture par un lutin grutier ou en l'occurrence une lutine grutière.

Bref, voici le code :

import re
from collections import deque
from io import StringIO
from typing import Dict, List, Iterable, Iterator, MutableSequence, Sequence
from typing_extensions import Protocol
class Crane(Protocol):
 def load(self, stacks: Sequence[MutableSequence[str]],
 labels: Iterable[str]) -> None:
 ...
 def move(self, orig: str, dest: str, n: int) -> None:
 ...
 def top(self) -> str:
 ...
class CrateMover:
 def __init__(self) -> None:
 self.stacks = {} # type: Dict[str, MutableSequence[str]]
 self.labels = [] # type: List[str]
 def load(self, stacks: Sequence[MutableSequence[str]],
 labels: Iterable[str]) -> None:
 for stack, label in zip(stacks, labels):
 self.stacks[label] = stack
 for label in labels:
 self.labels.append(label)
 def top(self) -> str:
 result = StringIO()
 for label in self.labels:
 result.write(self.stacks[label][-1])
 return result.getvalue()
class CrateMover9000(CrateMover):
 def __init__(self, *args, **kwargs) -> None:
 super().__init__()
 def move(self, orig: str, dest: str, n: int) -> None:
 orig_stack = self.stacks[orig]
 dest_stack = self.stacks[dest]
 for _ in range(n):
 dest_stack.append(orig_stack.pop())
class CrateMover9001(CrateMover):
 def __init__(self, *args, **kwargs) -> None:
 super().__init__()
 def move(self, orig: str, dest: str, n: int) -> None:
 orig_stack = self.stacks[orig]
 dest_stack = self.stacks[dest]
 temp_stack = deque() # type: deque[str]
 for _ in range(n):
 temp_stack.appendleft(orig_stack.pop())
 dest_stack.extend(temp_stack)
def solve(lines: Iterator[str], crane: Crane) -> str:
 re_crates = re.compile(r'^\s*\[')
 stacks = [] # type: List[deque[str]]
 # First lines are crate stack descriptions
 for line in lines:
 if re_crates.match(line):
 # This line describes stacked crates
 for i, label in enumerate(line[1:len(line):4]):
 if i >= len(stacks):
 stacks.append(deque())
 stack = stacks[i]
 if label != ' ':
 stack.appendleft(label)
 else:
 # This line provides the labels of crate stacks
 break
 # Current line provides the labels of crate stacks
 labels = line[1:len(line):4]
 # We have enough data to load the crane with crate stacks
 crane.load(stacks, labels)
 # Next line is a blank one
 s = next(lines)
 # Next lines are crate moving instructions
 re_instruction = re.compile(r'^move (\d+) from (.) to (.)$')
 for line in lines:
 m = re_instruction.match(line)
 if m is None:
 raise ValueError("unrecognized input line")
 n = int(m.group(1))
 orig = m.group(2)
 dest = m.group(3)
 crane.move(orig, dest, n)
 return crane.top()
def part1(data: Iterable[str]) -> str:
 crane = CrateMover9000()
 return solve(iter(data), crane)
def part2(data: Iterable[str]) -> str:
 crane = CrateMover9001()
 return solve(iter(data), crane)