79. 单词搜索

不要用 int[][] dir = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}}; 的写法了，下面这种比较好记。

class Solution {boolean[][] vis;public boolean exist(char[][] board, String word) {int m = board.length, n = board[0].length;vis = new boolean[m][n];for(int i = 0; i < m; i++){for(int j = 0; j < n; j++){if(dfs(board, i, j, word, 0)) return true;}}return false;}boolean dfs(char[][] board, int x, int y, String word, int ind){int m = board.length, n = board[0].length;if(x < 0 || x >= m || y < 0 || y >= n || word.charAt(ind) != board[x][y] || vis[x][y]) return false;if(ind == word.length() - 1) return true;vis[x][y] = true;if(dfs(board, x + 1, y, word, ind + 1)) return true;if(dfs(board, x, y + 1, word, ind + 1)) return true;if(dfs(board, x - 1, y, word, ind + 1)) return true;if(dfs(board, x, y - 1, word, ind + 1)) return true;vis[x][y] = false;return false;}
}