D-3.md

🔮 Question

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases. Note: For the purpose of this problem, we define empty string as valid palindrome.
Example 1:
Input: "A man, a plan, a canal: Panama"
Output: true
Example 2:
Input: "race a car"
Output: false
Constraints:
s consists only of printable ASCII characters.

🐉 Solution

class Solution {
    public boolean isPalindrome(String s) {
        if(s.equals("")){
            return true;
        }
     s=s.replaceAll("[^A-Za-z0-9]","");
        String st=s;
        StringBuilder revs=new StringBuilder(s);
        revs.reverse();
        String res=revs.toString();
        boolean ans=false;
        if(st.equalsIgnoreCase(res)){
            ans=true;
        }
        else{
            ans=false;
        }
        return ans;
    }
}