LC 63
Unique Paths II
Medium · LC 1–100
Candidate solution routes
Primary
FreeGrid 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: 0.740 · 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.