018. Valid palindromes

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One 、code

1.1 Title Description

LeetCode Address

1.2 Answer key

class Solution {
    
    public boolean isPalindrome(String s) {
    
        int i = 0;
        int j = s.length() - 1;
        while(i < j){
    
            char ch1 = s.charAt(i);
            char ch2 = s.charAt(j);
            if(!Character.isLetterOrDigit(ch1)){
    
                i++;
                continue;
            }
            if(!Character.isLetterOrDigit(ch2)){
    
                j--;
                continue;
            }
            ch1 = Character.toLowerCase(ch1);
            ch2 = Character.toLowerCase(ch2);
            if(ch1 != ch2){
    
                return false;
            }
            i++;
            j--;
        }
        return true;
    }
}

Two 、 summary

String class ：

• s.charAt() Method to return the characters at the specified index . Index range is from 0 To length() - 1.

Character class ：

• Character.isLetterOrDigit() // Judge is character or Numbers
• Character.isLowerCase()/Character.isUpperCase() // Determine case
  -Character.toLowerCase()/Character.toUpperCase() // Convert case