Leetcode#79 Word Search
依次枚举起始点,DFS+回溯
代码:
1 bool dfs(vector<vector<char> > &board, int r, int c, string word) { 2 int m = board.size(); 3 int n = board[0].size(); 4 int dir[4][2] = {{-1, 0}, {1, 0}, {0, -1}, {0, 1}}; 5 6 if (word.empty()) 7 return true; 8 9 if (r >= 0 && r < m && c >= 0 && c < n && board[r][c] == word[0]) { 10 for (int i = 0; i < 4; i++) { 11 char tmp = board[r][c]; 12 board[r][c] = 0; 13 if (dfs(board, r + dir[i][0], c + dir[i][1], word.substr(1))) 14 return true; 15 board[r][c] = tmp; 16 } 17 } 18 19 return false; 20 } 21 22 bool exist(vector<vector<char> > &board, string word) { 23 if (board.empty() || board[0].empty()) return false; 24 25 int m = board.size(); 26 int n = board[0].size(); 27 28 for (int i = 0; i < m; i++) 29 for (int j = 0; j < n; j++) 30 if (dfs(board, i, j, word)) 31 return true; 32 33 return false; 34 }