Find palindromes in an array of strings in Java

Question

Below is my code to find the palindromes in an array of strings using Brute Force method with O(n2) time complexity:

 for(int i=0;i<s.length;i++) {

            for(int j=i+1;j<s.length;j++) {

                if(s[i] == reverse(s[j])) {

                    count++;

                }

            }

        }

Can anyone tell me how to implement the above without using Hashing and with O(n) time complexity?

Answer 1

You can check the String as Palindrome like below: 

String st1 = "RACECAR";

int flag=0;   

    for (int j=0;j<=str1.length()-1 ;j++)   

    {   

     if (st1.charAt(j)!=st1.charAt(st1.length()-j-1))   

     {   

     flag=1;   

     break;   

     }   

    }  

  if(flag==1)   

  System.out.println("String is not a palindrome");   

  else   

    System.out.println("String is a palindrome"); 

Here is the Output :- String is a palindrome

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