125. Valid Palindrome*

Yingying_code

于 2016-12-27 22:22:37 发布

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分类专栏： leetcode Java String

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本文介绍了一种用于判断字符串是否为回文的有效算法，该算法只考虑字母数字字符且忽略大小写。通过双指针技术从两端向中间扫描，跳过非字母数字字符进行比较。

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Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

For example,
"A man, a plan, a canal: Panama" is a palindrome.
"race a car" is not a palindrome.

Note:
Have you consider that the string might be empty? This is a good question to ask during an interview.

My code:

    public boolean isPalindrome(String s) {
        if(s.length()==0) return true;
        int start = 0, end =s.length()-1;
        s = s.toLowerCase();
        while(start<end){
            while((s.charAt(start)>'z'||s.charAt(start)<'a'&&s.charAt(start)>'9'||s.charAt(start)<'0')&&start<end) start++;
            while((s.charAt(end)>'z'||s.charAt(end)<'a'&&s.charAt(end)>'9'||s.charAt(end)<'0')&&start<end)
            {end--;}
            if (s.charAt(start) !=s.charAt(end)) return false;
            start++;
            end--;
        }
        return true;
    }

总结：棒棒哒