DAY 9
0
Software Development

## 【Day 9】#79 - Word Search

Given a non-empty array of integers, every element appears twice except for one. Find that single one.
Given a 2D board and a word, find if the word exists in the grid.

The word can be constructed from letters of sequentially adjacent cell, where "adjacent" cells are those horizontally or vertically neighboring. The same letter cell may not be used more than once.

Example:

``````board =
[
['A','B','C','E'],
['S','F','C','S'],
['A','D','E','E']
]
Given word = "ABCCED", return true.
Given word = "SEE", return true.
Given word = "ABCB", return false.
``````

## 解法

``````class Solution {
public boolean exist(char[][] board, String word) {
if (board.length != 0 && board[0].length != 0)
for (int i = 0; i < board.length; i ++)
for (int j = 0; j < board[i].length; j ++)
if (backtracking(board, word, i, j, 0))
return true;
return false;
}

private boolean backtracking(char[][] board, String word, int row, int col, int pos) {
if (pos == word.length())
return true;
if (row < 0 || row >= board.length
|| col < 0 || col >= board[row].length
|| board[row][col] != word.charAt(pos))
return false;
board[row][col] ^= 256;
boolean res = backtracking(board, word, row + 1, col, pos + 1)
|| backtracking(board, word, row - 1, col, pos + 1)
|| backtracking(board, word, row, col + 1, pos + 1)
|| backtracking(board, word, row, col - 1, pos + 1);
board[row][col] ^= 256;

return res;
}
}
``````

LeetCode小試身手14