10. 正则表达式匹配 | Regular Expression Matching

[strengthen]

Given an input string (s) and a pattern (p), implement regular expression matching with support for '.' and '*'.

'.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial).

Note:

s could be empty and contains only lowercase letters a-z. p could be empty and contains only lowercase letters a-z, and characters like . or *. Example 1:

Input: s = "aa" p = "a" Output: false Explanation: "a" does not match the entire string "aa". Example 2:

Input: s = "aa" p = "a*" Output: true Explanation: '*' means zero or more of the precedeng element, 'a'. Therefore, by repeating 'a' once, it becomes "aa". Example 3:

Input: s = "ab" p = "." Output: true Explanation: "." means "zero or more (*) of any character (.)". Example 4:

Input: s = "aab" p = "cab" Output: true Explanation: c can be repeated 0 times, a can be repeated 1 time. Therefore it matches "aab". Example 5:

Input: s = "mississippi" p = "misisp*." Output: false 给定一个字符串 (s) 和一个字符模式 (p)。实现支持 '.' 和 '*' 的正则表达式匹配。

'.' 匹配任意单个字符。 '*' 匹配零个或多个前面的元素。 匹配应该覆盖整个字符串 (s) ，而不是部分字符串。

说明:

s 可能为空，且只包含从 a-z 的小写字母。 p 可能为空，且只包含从 a-z 的小写字母，以及字符 . 和 *。 示例 1:

输入: s = "aa" p = "a" 输出: false 解释: "a" 无法匹配 "aa" 整个字符串。 示例 2:

输入: s = "aa" p = "a*" 输出: true 解释: '*' 代表可匹配零个或多个前面的元素, 即可以匹配 'a' 。因此, 重复 'a' 一次, 字符串可变为 "aa"。 示例 3:

输入: s = "ab" p = "." 输出: true 解释: "." 表示可匹配零个或多个('*')任意字符('.')。 示例 4:

输入: s = "aab" p = "cab" 输出: true 解释: 'c' 可以不被重复, 'a' 可以被重复一次。因此可以匹配字符串 "aab"。 示例 5:

输入: s = "mississippi" p = "misisp*." 输出: false