Classic backtracking problem and I knew it the second I read it.
This is a classic backtracking problem: iterate over each cell as a potential starting point, and perform DFS to match the target word character by character. At each step, explore all four adjacent cells, marking the current cell as visited to avoid reuse, and backtrack if no path works.
Pro tip: Before coding, clarify edge cases like empty word, empty grid, and whether diagonal moves are allowed. Also mention that you can optimize by checking character frequency counts upfront to quickly reject impossible cases.
Confirm movement rules (only horizontal/vertical), no cell reuse, and handle edge cases like empty word or grid. Ask if the word must be found exactly once or if multiple paths are acceptable.
Use DFS with backtracking. For each cell that matches the first character, recursively search for the remaining characters in adjacent cells.
Mark the current cell as visited (e.g., temporarily change its value or use a visited matrix), explore all four directions, and unmark it when backtracking.
Add early termination if the word is longer than the total cells. Optionally, pre-check character frequencies to quickly return false if the grid lacks required characters.
Time complexity is O(N * 3^L) where N is the number of cells and L is the word length (since each step has up to 3 unvisited neighbors). Space complexity is O(L) for recursion stack.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.