Recursive Palindrome judge

• Topic Introduction:

          "Palindrome" is the correct reading, the opposite of reading all the same sentence. For example, "Who am I that I" using a recursive algorithm to detect palindrome algorithm is described as follows:

          A single or zero-character string is a palindrome.Any other string is a palindrome if the first and last characters are

          the same, and the string that remains, excepting those characters, is a palindrome.

• Design ideas:

          1. Analyzing string length (n), i.e., when 1 is 0 with a string of palindromes.

          1 and 2. If not match, then we need to string recursive determination, i.e., to get the first (n-1) characters of a (length-n) characters are compared, if the same is n-1, then comparison, so the cycle, there will be an end point.

          3. The end point is when n is 0 or 1, i.e. if this is a palindrome.

          4. recursive condition is: if the first (n-1) characters of a (length-n) identical characters, the string length - 1, not satisfied, then exit.

• code show as below

package javatask;

import java.util.Scanner;

public class Palindrome {
        static Scanner in=new Scanner(System.in);
        static char str[] = new char[99];
        public static void main(String [] args) 
        {
            System.out.println("请输入字符串");
            String a;
            a=in.next();
            if(Palindrome(a,a.length()))//如果是回文
                System.out.println("It's a palindrome");
             The else     // if not palindromic 
                System.out.println ( "Not It apos Palindrome A" ); 
        } 
    static  public  Boolean   Palindrome (A String, int n-) 
    { 
        int length = a.length ();
         IF (n-== n-== 0 ||. 1 )
             return  to true ;
         the else  
        { 
            IF (a.charAt (. 1-n-) == a.charAt (n--length)) // the first character to the last character comparison 
                return Palindrome (a, --n); // recursive repeatedly determines 
            the else  
                return  to false ; //Not a palindrome 
        } 
        
    } 
}

• Screenshot operating results

          

          

          

• Programming summary analysis

           This question is more difficult point of it is to use recursion to determine how and how to extract a character in a string operation.