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Word Search II
Learn how to solve the 'Word Search II' problem. This detailed resource details brute force and optimized approaches.
Problem Statement
Easy
Given an m x n board of characters and a list of strings words, return all words on the board.
Each word must be constructed from letters of sequentially adjacent cells, where adjacent cells are horizontally or vertically neighboring. The same letter cell may not be used more than once in a word.
Write a function findWords(board: List[List[str]], words: List[str]) -> List[str].
Constraints
- •m == len(board)
- •n == len(board[i])
- •1 <= m, n <= 12
- •board[i][j] is a lowercase English letter
- •1 <= len(words) <= 3 * 10^4
- •1 <= len(words[i]) <= 10
- •words consist of lowercase English letters
- •All the strings in words are unique
Examples
Example 1
Input
board = [["o","a","a","n"],["e","t","a","e"],["i","h","k","r"],["i","f","l","v"]], words = ["oath","pea","eat","rain"]
Output
["oath","eat"]
Explanation
The words "oath" and "eat" can be found on the board. "pea" and "rain" cannot.
Example 2
Input
board = [["a","b"],["c","d"]], words = ["abcb"]
Output
[]
Explanation
The word "abcb" requires using the 'b' cell twice, which is invalid.
Need a Hint?
Analyze the input constraints. Try sorting first (O(n log n)) or using a hash map/set to track seen elements in O(n) time.
Edge Cases to Watch
- Empty list or null input variables
- Single item lists/arrays
- Extremely large input bounds causing integer or stack overflow
Ready to Solve?
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