遞歸方法判斷回文

（1）  使用遞歸方式判斷某個字串是否是回文（ palindrome ）；

“回文”是指正着讀、反着讀都一樣的句子。比如“我是誰是我”

使用遞歸算法檢測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 遞歸回文;
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();//從鍵盤輸入
        for(int i=0;i<s.length();i++) {//轉化為字符數組
        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;//字符個數為1，必為回文
        if (a[low] != a[high] || low >= high) {//第一個字符與最后一個字符比較
            return false;
        }
        return isHuiwen(a, low + 1, high -1,length -2);//遞歸
    }
}

運行截圖：