回文

（1） 使用递归方式判断某个字串是否是回文（ palindrome ）；

“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.

package huiwen;
import java.util.*;
public class Huiwen{
    static Scanner  x=new Scanner(System.in);
    static char strs[] = new char[1000];
    static int j=0;
    public static void main(String[] args) {
        String s = x.next();//从键盘输入
        for(int i=0;i<s.length();i++) {//转化为字符数组
        strs[j] = s.charAt(i);
        j++;
        }
        boolean huiwen = isHuiwen(strs, 0, j-1,j);
        System.out.println(huiwen);
    }
    public static boolean isHuiwen(char a[],int low,int high,int length){
        if(length == 1 || length == 0)
            return true;//字符个数为1，必为回文
        if (a[low] != a[high] || low >= high) {//第一个字符与最后一个字符比较
            return false;
        }
        return isHuiwen(a, low + 1, high -1,length -2);//递归
    }
}