Leetcode#79 Word Search

原题地址

依次枚举起始点，DFS+回溯

代码：

 bool dfs(vector<vector<char> > &board, int r, int c, string word) {
   int m = board.size();
   int n = board[].size();
   int dir[][] = {{-, }, {, }, {, -}, {, }};

   if (word.empty())
     return true;

   if (r >=  && r < m && c >=  && c < n && board[r][c] == word[]) {
     for (int i = ; i < ; i++) {
       char tmp = board[r][c];
       board[r][c] = ;
       if (dfs(board, r + dir[i][], c + dir[i][], word.substr()))
         return true;
       board[r][c] = tmp;
     }
   }

   return false;
 }

 bool exist(vector<vector<char> > &board, string word) {
   if (board.empty() || board[].empty()) return false;

   int m = board.size();
   int n = board[].size();

   for (int i = ; i < m; i++)
     for (int j = ; j < n; j++)
       if (dfs(board, i, j, word))
         return true;

   return false;
 }