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leecode 回文字符串加强版

2024-07-10 15:51:20   223人阅读

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.

只考虑数字和字母，字母大小写都一样，判断是否是回文。重点是忽略非非字母和数字。比较简单。

 1 public class Solution { 2     public boolean isPalindrome(String s) { 3           4         int low=0; 5         int high=s.length()-1; 6         String s1=s.toLowerCase(); 7         while(low<high) 8         { 9           10             while(low<high)11             {12                char c=s1.charAt(low);13                if((c>=‘a‘&&c<=‘z‘)||(c>=‘0‘&&c<=‘9‘))14                {15                    break;16                }17                else  low++;18                 19             }20             21              while(low<high)22             {23                char c=s1.charAt(high);24                if((c>=‘a‘&&c<=‘z‘)||(c>=‘0‘&&c<=‘9‘))25                {26                    break;27                }else high--;28                 29             }30             31             32             33             if(s1.charAt(low)==s1.charAt(high)) 34             {35                 low++;36                 high--;37             }38             else39             {40                 return false;41             }42            43             44             45         }46         47         return true;48         49         50     }51 }

 


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