LeetCode 刷题记录: 79. Word Search [Python]

原题

https://leetcode.com/problems/word-search/

Given a 2D board and a word, find if the word exists in the grid.

The word can be constructed from letters of sequentially adjacent cell, where “adjacent” cells are those horizontally or vertically neighboring. The same letter cell may not be used more than once.

思路

DFS。四个方向搜寻即可。

代码

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class Solution:
def exist(self, board: List[List[str]], word: str) -> bool:
if not board: return False
for i in range(len(board)):
for j in range(len(board[0])):
if self.dfs(board,i,j,word): return True
return False
def dfs(self, board, i, j, word):
if len(word)==0: return True
if i<0 or i>=len(board) or j<0 or j>=len(board[0]) or word[0]!=board[i][j]: return False
tmp,board[i][j]=board[i][j],'#'
res=self.dfs(board,i-1,j,word[1:]) or self.dfs(board,i+1,j,word[1:]) or self.dfs(board,i,j-1,word[1:]) or self.dfs(board, i, j+1, word[1:])
board[i][j]=tmp
return res

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