Generating All Permutations

itertools.permutations or swap-based backtracking for lex order.

Try this in Python

from itertools import permutations
print(len(list(permutations(range(5)))))

Key takeaways

• Factorial growth—n ≤ 8 brute is already heavy.
• Use next_permutation pattern on arrays for O(n!) * n if needed.
• Handle duplicates with multiset tricks.