[painbaba]

Summary

solutions/python/practice343.py had no explanation beyond the header. This adds a beginner-friendly plain-English walkthrough of the rank-transform trick: what a rank is, how sorted(set(...)) + zip + dict build the value-to-rank lookup table, why duplicates share a rank and ranks have no gaps, plus a small worked example and the time (O(n log n)) and space (O(n)) complexity.

Comments only — the diff is +24/−0 and no code line is touched, so the solution and its example output are unchanged. Also added the Note: line required by the repo's header convention for changed solution files.

Related issue

Closes #191

Validation

• python -I solutions/python/practice343.py on Windows, Python 3.11.15: the three example outputs are exactly the previously commented values ([5,3,4,2,8,6,7,1,3], [4,1,2,3], [1,1,1]).
• git diff shows insertions only (no deletions) — confirming a comments-only change.
• Repository header validator (python -I scripts/check_solution_headers.py --base upstream/main --head HEAD): passed.

Checklist

• The solution includes the required problem, source, and note header comment.
• The file is in the correct solutions/<language>/ folder and follows the practice<n> naming convention.
• I ran the solution and checked that it works.
• I have kept this pull request focused on one change.