Valid Palindrome

最新推荐文章于 2024-01-04 12:53:14 发布

cgdong2014

最新推荐文章于 2024-01-04 12:53:14 发布

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本文介绍了一种算法，用于判断一个字符串是否为回文，重点考虑了仅包含字母数字字符的情况，并忽略大小写差异。该算法首先将所有非字母数字字符从原始字符串中移除，并转换为小写形式。然后通过比较字符串首尾字符来确定其是否为回文。

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.

For the purpose of this problem, we define empty string as valid palindrome.

思路： Using a string builder to storage the string without blank.
Check the sb.charAt(i) == sb.charAt(len - 1 - i);

易错点：别忘记还有数字

public class Solution {
    public boolean isPalindrome(String s) {
        if(s.length() < 1){
            return true;
        }
        s = s.toLowerCase();
        s.trim();
        StringBuilder sb = new StringBuilder();
        for(int i = 0; i < s.length(); i++){
            char c = s.charAt(i);
            if((c >= 'a' && c <= 'z') || (c >='0' && c <= '9')){
                sb.append(c);
            }
        }
        for(int i = 0; i < sb.length()/2; i++){
            if(sb.charAt(i) != sb.charAt(sb.length() - 1 - i)){
                return false;
            }
        }
        return true;
    }
}