125. Valid Palindrome java solutions

最新推荐文章于 2024-01-04 12:53:14 发布

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最新推荐文章于 2024-01-04 12:53:14 发布

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原文链接：http://www.cnblogs.com/guoguolan/p/5659365.html

本文介绍了一种判断字符串是否为回文的方法，特别考虑了只包含字母和数字的情况，并忽略大小写。通过一个Java实现的例子，展示了如何跳过非字母数字字符进行比较。

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.

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 1 public class Solution {
 2     public boolean isPalindrome(String s) {
 3         if(s.trim() == "") return true;
 4         int i = 0,j = s.length()-1;
 5         char c1,c2;
 6         while(i <= j){
 7             c1 = s.charAt(i);
 8             c2 = s.charAt(j);
 9             if(!Character.isLetterOrDigit(c1)) i++;
10             if(!Character.isLetterOrDigit(c2)) j--;
11             if(Character.isLetterOrDigit(c1) && Character.isLetterOrDigit(c2)){
12                 if(Character.toLowerCase(c1) != Character.toLowerCase(c2)) return false;
13                 i++;
14                 j--;
15             }
16         }
17         return true;
18     }
19 }