LeetCode 10 Regular Expression Matching （正则表达式匹配）

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翻译

实现支持“.”和“*”的正则表达式匹配。“.” 匹配支持单个字符“*” 匹配零个或多个前面的元素匹配应该覆盖到整个输入的字符串（而不是局部的）。该函数的原型应该是：bool isMatch(const char * s, const char * p)示例：isMatch("aa","a") → falseisMatch("aa","aa") → trueisMatch("aaa","aa") → falseisMatch("aa", "a*") → trueisMatch("aa", ".*") → trueisMatch("ab", ".*") → trueisMatch("aab", "c*a*b") → true

原文

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).The function prototype should be:bool isMatch(const char *s, const char *p)Some examples:isMatch("aa","a") → falseisMatch("aa","aa") → trueisMatch("aaa","aa") → falseisMatch("aa", "a*") → trueisMatch("aa", ".*") → trueisMatch("ab", ".*") → trueisMatch("aab", "c*a*b") → true

C#，递归

public class Solution{    public bool IsMatch(string s, string p)    {        if (p.Length == 0)            return s.Length == 0;        if (p.Length == 1)            return (s.Length == 1) && (p[0] == s[0] || p[0] == '.');        if (p[1] != '*')        {            if (s.Length == 0)                return false;            else                return (s[0] == p[0] || p[0] == '.')                       && IsMatch(s.Substring(1), p.Substring(1));        }        else        {            while (s.Length > 0 && (p[0] == s[0] || p[0] == '.'))            {                if (IsMatch(s, p.Substring(2)))                    return true;                s = s.Substring(1);            }            return IsMatch(s, p.Substring(2));        }    }}

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