LeetCode

题目：

Implement wildcard pattern matching with support for '?' and '*'.

'?' Matches any single character.
'*' Matches any sequence of characters (including the empty sequence).

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", "*") → true
isMatch("aa", "a*") → true
isMatch("ab", "?*") → true
isMatch("aab", "c*a*b") → false

思路：
这题其实比Regular Expression Matching那道题容易，判断p中"*"的情况更简单。

package dp;

public class WildcardMatching {

    public boolean isMatch(String s, String p) {
        int slen = s.length();
        int plen = p.length();
        boolean[][] dp = new boolean[slen + 1][plen + 1];
        dp[0][0] = true;
        for (int i = 1; i <= plen; ++i)
            dp[0][i] = p.charAt(i - 1) == '*' ? dp[0][i - 1] : false;
        for (int i = 1; i <= slen; ++i)
            dp[i][0] = false;
        for (int i = 1; i <= slen; ++i) {
            for (int j = 1; j <= plen; ++j) {
                if (p.charAt(j - 1) == '*') {
                    dp[i][j] = dp[i - 1][j - 1] || dp[i - 1][j] || dp[i][j - 1];
                } else {
                    dp[i][j] = match(s.charAt(i - 1), p.charAt(j - 1)) && dp[i - 1][j - 1];
                }
            }
        }
        
        return dp[slen][plen];
    }
    
    private boolean match(char a, char b) {
        if (b == '?' || b == '*')
            return true;
        return a == b;
    }
    
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        WildcardMatching w = new WildcardMatching();
        System.out.println(w.isMatch("aa","a"));
        System.out.println(w.isMatch("aa","aa"));
        System.out.println(w.isMatch("aaa","aa"));
        System.out.println(w.isMatch("aa", "*"));
        System.out.println(w.isMatch("aa", "a*"));
        System.out.println(w.isMatch("ab", "?*"));
        System.out.println(w.isMatch("aab", "c*a*b"));
        
    }

}