Valid Palindrome

最新推荐文章于 2024-01-04 12:53:14 发布

iteye_6755

最新推荐文章于 2024-01-04 12:53:14 发布

阅读量56

点赞数

分类专栏： leetcode

leetcode 专栏收录该内容

193 篇文章

订阅专栏

本文介绍如何通过编程判断给定字符串是否为回文串，考虑只包含字母数字字符并忽略大小写。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

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.

public class Solution {
    public boolean isPalindrome(String s) {
        if (s.length() == 0) {
        	return true;
        }
        s = s.toUpperCase();
        int first = 0;
        int end = s.length()-1;
        while (first < end) {
        	if ((s.charAt(first)<'A' || s.charAt(first)>'Z') && (s.charAt(first)>'9' || s.charAt(first)<'0' )) {
        		first++;
        		continue;
        	}
        	if ((s.charAt(end)<'A' || s.charAt(end)>'Z') && (s.charAt(end)>'9' || s.charAt(end)<'0' )) {
        		end--;
        		continue;
        	}
        	if (s.charAt(first) == s.charAt(end)) {
        		first++;
        		end--;
        	} else {
        		return false;
        	}
        }
        return true;
    }
}