Clarify the problem constraints (e.g., whether diagonal moves are allowed, if cells can be reused, and grid dimensions) before diving into the algorithm. Then, propose a depth-first search (DFS) with backtracking from each cell, exploring all 8 directions (or 4 if diagonals are excluded) to match the word character by character. Discuss time and space complexity, and consider optimizations like early termination or pruning.
Pro tip: Mention that you would handle edge cases such as an empty grid, word longer than total cells, or repeated characters, and discuss how to avoid revisiting cells (e.g., marking visited cells temporarily). This shows attention to detail and robustness, which is highly valued at Uber.
Ask about grid dimensions, allowed directions (horizontal, vertical, diagonal), whether cells can be reused, and if the word can be empty. Confirm input types and expected output.
Explain that you will iterate over each cell as a starting point and perform DFS/backtracking to match the word. Mention that you will explore all valid directions from each cell.
Describe how to recursively check the next character in each direction, marking cells as visited to avoid reuse, and unmarking them upon backtracking. Include base cases for success and failure.
State the time complexity (O(N * M * 8^L) where L is word length) and space complexity (O(L) for recursion stack). Discuss potential optimizations like early exit if the first character doesn't match or using a trie for multiple words.
Walk through a small example, including edge cases like word not present, single-cell grid, or word with repeated characters. Verify the algorithm handles them correctly.
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