(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 } }