leetcode79: word_search

[carloscn]

描述

给定一个 m x n 二维字符网格 board 和一个字符串单词 word 。如果 word 存在于网格中，返回 true ；否则，返回 false 。

单词必须按照字母顺序，通过相邻的单元格内的字母构成，其中“相邻”单元格是那些水平相邻或垂直相邻的单元格。同一个单元格内的字母不允许被重复使用。

输入：board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "ABCCED" 输出：true

输入：board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "SEE" 输出：true

输入：board = [["A","B","C","E"],["S","F","C","S"],["A","D","E","E"]], word = "ABCB" 输出：false

提示：

m == board.length n = board[i].length 1 <= m, n <= 6 1 <= word.length <= 15 board 和 word 仅由大小写英文字母组成

[carloscn]

分析

• 我们需要做个单元函数，这个单元函数的功能就是，指定的点，和指定的字母，上下左右的位置是否能找到，如果能找到返回true，不能找到返回false。
• 需要有一层循环来分别调用这个单元函数，四个方向都要执行，这是个递归操作。