LC 62
Unique Paths
Medium · LC 1–100
Candidate solution routes
Grid dynamic programming
Invariant: When cell (r,c) is processed, every predecessor state already meets its definition; the new state aggregates every legal way to enter the cell exactly as required.
candidate confidence: 0.555 · metadata_only
Combinatorial counting / inclusion-exclusion
Invariant: Every valid outcome maps to one counting representation, or to a known fixed multiplicity that is explicitly corrected.
candidate confidence: 0.665 · metadata_only
Linear dynamic programming
Invariant: After processing i, every state through i equals the true value under its definition, and every future transition reads only these finalized states.
candidate confidence: 0.470 · metadata_only
How to use this page
Read the statement and constraints first, then validate recognition signals, invariant, and complexity. Candidate score is not correctness evidence.