Permutation Algorithms

[aesteve]

Permutation Algorithms

Description

Adds a few common permutation algorithms:

• the naive, recursive way, including a variant to avoid generating duplicates
• Heap's algorithm
• Steinhaus-Johnson-Trotter algorithm

Type of change

Please delete options that are not relevant.

• New feature (non-breaking change which adds functionality)

Checklist:

• I ran bellow commands using the latest version of rust nightly.
• I ran cargo clippy --all -- -D warnings just before my last commit and fixed any issue that was found.
• I ran cargo fmt just before my last commit.
• I ran cargo test just before my last commit and all tests passed.
• I checked COUNTRIBUTING.md and my code follows its guidelines.

Note: tests are running under 300ms on my laptop, let me know if it's too slow on CI. If so, we can definitely reduce MAX_SIZE to 6 or less.

[siriak]

Looks good, thanks!