leetcode Word Search 待解决？

终于搞定了这个DFS，最近这个DFS写的很不顺手，我一直以为递归这种东西只是在解重构时比较麻烦，现在看来，连最简单的返回true和false的逻辑关系都不能说one hundred present 搞定。

人品啊TLE:

 class Solution {
 public:
 bool legal(int i, int j, vector<vector<char>> board)
 {
     if (i >=  && i < board.size() && j >=  && j < board[i].size())
         return true;
     return false;
 }

    bool dfs(vector<vector<char>>& board, string word, int t, int i, int j, vector<vector<bool>> visited)
 {
     if (t == word.length())
         return true;
     if (board[i][j] == word[t])
     {
         visited[i][j] = true;
         if (legal(i - , j, board) && !visited[i - ][j] && dfs(board, word, t + , i - , j, visited))
             return true;
         if (legal(i, j + , board) && !visited[i][j + ] && dfs(board, word, t + , i, j + , visited))
             return true;
         if (legal(i + , j, board) && !visited[i + ][j] && dfs(board, word, t + , i + , j, visited))
             return true;
         if (legal(i, j - , board) && !visited[i][j - ] && dfs(board, word, t + , i, j - , visited))
             return true;
     }
     visited[i][j] = false;
     return false;
 }

 bool exist(vector<vector<char>>& board, string word)
 {
     int m = board.size();
     int n = board[].size();
     vector<vector<bool>> visited(m, vector<bool>(n, false));
     for (int i = ; i < board.size(); i++)
     {
         for (int j = ; j < board[].size(); j++)
         {
             if (dfs(board, word, , i, j, visited))
                 return true;
         }
     }
     return false;
 }
 };

为什么？

下面的依然是超时的， 无论怎么尝试都是超时的，觉得和提交的AC代码并没有什么区别啊？

 #include<iostream>
 #include<vector>

 using namespace std;

 bool isLegal(int i, int j, vector<vector<char>> board)
 {
     int H = board.size();
     int L = board[].size();
     if (i >=  && i < H&&j >=  && j < L)
         return true;
     return false;
 }

 bool searchWord(vector<vector<char>> board, vector<vector<bool>> visited, string word, int i, int j, int index)
 {
     if (index >= word.length())
     {
         return true;
     }
     /*if (word[index] == board[i][j])
     {*/
         visited[i][j] = true;
         int dx[] = { , , -,  };
         int dy[] = { , , , - };

         for (int x = ; x < ; ++x)
         {
             int ii = i + dx[x];
             int jj = j + dy[x];
             if (isLegal(ii, jj, board) && !visited[ii][jj] && board[ii][jj] == word[index] && searchWord(board, visited, word, ii, jj, index + ))
                 return true;
         }

         /*if (isLegal(i - 1, j, board) && !visited[i - 1][j] && board[i - 1][j]==word[index] && searchWord(board, visited, word, i - 1, j, index + 1))
             return true;
         if (isLegal(i, j - 1, board) && !visited[i][j - 1] && board[i][j - 1] == word[index] && searchWord(board, visited, word, i, j - 1, index + 1))
             return true;
         if (isLegal(i + 1, j, board) && !visited[i + 1][j] && board[i + 1][j] == word[index] && searchWord(board, visited, word, i + 1, j, index + 1))
             return true;
         if (isLegal(i, j + 1, board) && !visited[i][j + 1] && board[i][j + 1] == word[index] && searchWord(board, visited, word, i, j + 1, index + 1))
             return true;*/
     /*}*/
     visited[i][j] = false;
     return false;
 }

 bool exist(vector<vector<char>>& board, string word) {
     if (word.empty()) return false;
     int H = board.size();
     int L = board[].size();
     int i, j;
     vector<vector<bool>> visited(H, vector<bool>(L, false));
     for (i = ; i < H; i++)
     {
         for (j = ; j < L; j++)
         {
             if (word[]==board[i][j]&&searchWord(board, visited, word, i, j, ))
             {
                 return true;
             }
         }
     }
     return false;
 }

 int main()
 {
     char boardArray[][] =
     {
         { 'A', 'B', 'C', 'E' },
         { 'S', 'F', 'C', 'S' },
         { 'A', 'D', 'E', 'E' }
     };
     vector<vector<char>> board1();
     for (int i = ; i < ; i++)
     {
         vector<char> temp();
         temp[] = 'A';
         board1[i] = temp;
         for (int j = ; j < ; j++)
         {
             board1[i][j] = boardArray[i][j];
         }
     }

     if (exist(board1, "ABCCED"))
         cout << <<endl;
     else
         cout <<  << endl;
 }