LC 79

Word Search

Medium · LC 1–100 + first-family candidate

arraybacktrackingdepth-first-searchmatrixstring
Free

Candidate solution routes

Primary

Constraint-satisfaction backtracking

Free

Invariant: At recursion entry, the partial assignment satisfies every activated constraint and every auxiliary set/count exactly matches it; a pruned branch has no legal completion.

candidate confidence: 0.740 · metadata_only

Alternate 1

Grid Flood Fill

Free

Invariant: Every cell in the frontier has passed bounds and predicate checks and is already marked; expansion only considers its eligible neighbors.

candidate confidence: 0.557 · metadata_only

Alternate 2

DFS Components and Reachability

Free

Invariant: Once marked visited, a vertex belongs to the component represented by the current search and can never join a later component.

candidate confidence: 0.610 · 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.