使用递归方式判断某个字串是否是回文（ palindrome ）

Posted 2021-01-12 李胜明

 

   

“回文”是指正着读、反着读都一样的句子。比如“我是谁是我” 使用递归算法检测回文的算法描述如下： 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.

  回文的代码如下：

package Huiwen;
import java.util.Scanner;
public class huiwen {
public static boolean isPalindrome(String s,int i,int j){
if(i > j)
throw new IllegalArgumentException();
if(i == j)
return true;
else{
return (s.charAt(i) == s.charAt(j)) && isPalindrome(s,i+1,j-1);
}
}

public static void main(String[] args){
Scanner in=new Scanner(System.in);
String s = in.nextLine();
int i = 0;
int j = s.length() - 1;
System.out.println(s + " is Palindrome? " + huiwen .isPalindrome(s, i, j));
}
}

代码截图：