[Python] Simple Solution | DFS
python\nclass Solution(object):\n    def exist(self, board, word):\n        for i in xrange(len(board)):\n            for j in xrange(len(board[0])):\n         
```python\nclass Solution(object):\n    def exist(self, board, word):\n        for i in xrange(len(board)):\n            for j in xrange(len(board[0])):\n                if self.dfs(board, word, i, j): return True\n        return False\n                \n    def dfs(self, board, word, i, j):\n        if i <= -1 or i >= len(board) or j <= -1 or j >= len(board[0]): return False\n        if board[i][j] == -1 or board[i][j] != word[0]: return False\n        if len(word) == 1: return True\n        \n        temp, board[i][j] = board[i][j], -1\n        if self.dfs(board, word[1:], i-1, j): return True\n        if self.dfs(board, word[1:], i+1, j): return True\n        if self.dfs(board, word[1:], i, j-1): return True\n        if self.dfs(board, word[1:], i, j+1): return True\n        board[i][j] = temp\n        return False\n```
['Depth-First Search', 'Python', 'Python3']