目录
程序清单18_1ComputeFactorial.java
程序清单18_2ComputeFibonacci.java
程序清单18_3RecursivePalindromeUsingSubstring.java
程序清单18_1ComputeFactorial.java
package chapter_18;import java.util.Scanner;public class 程序清单18_1ComputeFactorial {public static void main(String[] args) {Scanner input = new Scanner(System.in);System.out.print("Enter a nonnegative integer:");int n = input.nextInt();System.out.println("Factorial of " + n + " is " + factorial(n));}public static long factorial(int n) {if(n == 0)return 1;else return n * factorial(n - 1);}
}
输出结果
Enter a nonnegative integer:4
Factorial of 4 is 24
程序清单18_2ComputeFibonacci.java
package chapter_18;import java.util.Scanner;public class 程序清单18_2ComputeFibonacci {public static void main(String[] args) {Scanner input = new Scanner(System.in);System.out.print("Enter an index for a Fibonacci number:");int index = input.nextInt();System.out.println("The Fibonacci number at index "+ index+" is " + fib(index));}public static long fib(long index) {if (index == 0) return 0;else if(index == 1)return 1;else return fib(index - 1) + fib(index - 2);}
}
输出结果
Enter an index for a Fibonacci number:7
The Fibonacci number at index 7 is 13
程序清单18_3RecursivePalindromeUsingSubstring.java
package chapter_18;public class 程序清单18_3RecursivePalindromeUsingSubstring {public static boolean isPalindrome(String s) {if(s.length() <= 1)return true;else if(s.charAt(0) != s.charAt(s.length() - 1))return false;else return isPalindrome(s.substring(1, s.length()-1));}public static void main(String[] args) {System.out.println("Is moon a palindrome? "+isPalindrome("moon"));System.out.println("Is noon a palindrome? "+isPalindrome("noon"));System.out.println("Is a a palindrome? "+isPalindrome("a"));System.out.println("Is aba a palindrome? "+isPalindrome("aba"));System.out.println("Is ab a palindrome? "+isPalindrome("ab"));}}