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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") → false
isMatch("aa","aa") → true
isMatch("aaa","aa") → false
isMatch("aa", "a*") → true
isMatch("aa", ".*") → true
isMatch("ab", ".*") → true
isMatch("aab", "c*a*b") → true
题意
带通配符带字符串匹配。
. 匹配任意的单个字符* 匹配前一个字符的零个或者多个出现
1 //摘自《代码之美》 2 // 字符 含义 3 // . 匹配任意的单个字符 4 // ^ 匹配输入字符串的开头 5 // $ 匹配输入字符串的结尾 6 // * 匹配前一个字符的零个或者多个出现 7 #include <stdio.h> 8 int matchhere(char *regexp, char *text); 9 10 int matchstar(int c, char *regexp, char *text) {// matchstar: search for c*regexp at beginning of text 11 do {// a * matches zero or more instances 12 if (matchhere(regexp, text)) return 1; 13 } while (*text != ‘\0‘ && (*text++ == c || c == ‘.‘)); 14 return 0; 15 } 16 int matchhere(char *regexp, char *text) {// matchhere: search for regexp at beginning of text 17 if (regexp[0] == ‘\0‘) return 1; 18 if (regexp[1] == ‘*‘) return matchstar(regexp[0], regexp+2, text); 19 if (regexp[0] == ‘$‘ && regexp[1] == ‘\0‘) return *text == ‘\0‘; 20 if (*text!=‘\0‘ && (regexp[0]==‘.‘ || regexp[0]==*text)) return matchhere(regexp+1, text+1); 21 return 0; 22 } 23 24 int match(char *regexp, char *text) {// match: search for regexp anywhere in text 25 if (regexp[0] == ‘^‘) return matchhere(regexp+1, text); 26 do {// must look even if string is empty 27 if (matchhere(regexp, text)) return 1; 28 } while (*text++ != ‘\0‘); 29 return 0; 30 }
下面是自己的关于此题的代码。
1 bool isMatch(char* s, char* p); 2 bool matchstar(int c,char *s,char *p) 3 { 4 do {// a * matches zero or more instances 5 if (isMatch(s, p)) return 1; 6 } while (*s != ‘\0‘ && (*s++ == c || c == ‘.‘)); 7 return 0; 8 } 9 bool isMatch(char* s, char* p) { 10 if(p[0]==‘\0‘ && s[0]==‘\0‘) return 1; 11 if(p[1]==‘*‘) return matchstar(p[0], s,p+2); 12 if(*s!=‘\0‘ && (p[0]==‘.‘ || *s==p[0])) return isMatch(s+1,p+1); 13 return 0; 14 15 }
LeetCode.010 Regular Expression Matching
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原文地址：http://www.cnblogs.com/madking/p/4658538.html
