Regular Expression Matching

题目

'.'

'*'

'.' 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

方法

private boolean getMatch(String s, int lenS, int curS, String p, int lenP, int curP) {

if (curP == lenP) {
return curS == lenS;
}
if (curP + 1 == lenP || p.charAt(curP + 1) != '*') {
if (curS == lenS) {
return false;
}
return (p.charAt(curP) == s.charAt(curS) || p.charAt(curP) == '.') && getMatch(s, lenS, curS + 1, p, lenP, curP + 1);
}

while (curS < lenS && (s.charAt(curS) == p.charAt(curP) || p.charAt(curP) == '.')) {
if (getMatch(s, lenS, curS, p, lenP, curP + 2)) {
return true;
}
curS++;
}
return getMatch(s, lenS, curS, p, lenP, curP + 2);
}
public boolean isMatch(String s, String p) {
if ((s == null && p == null) || (s.length() == 0 && p.length() == 0)) {
return true;
}
int lenS = s.length();
int lenP = p.length();
return getMatch(s, lenS, 0, p, lenP, 0);
}