面试总结--递归2

/**
* 汉诺塔问题
*
* @param num
*            盘子数
* @param a
*            柱子a
* @param b
*            柱子b
* @param c
*            柱子c
*/
public static void hannota(int num, char a, char b, char c) {
if (num == 1) {
move(1, a, c);
return;
} else {
hannota(num - 1, a, c, b);
move(num - 1, a, c);
hannota(num - 1, b, a, c);
}
}
static void move(int num, char source, char target) {
System.out.println("moving " + num + " from " + source + " to "
+ target);
}

public class Recursion {
public static void main(String[] args) {
System.out.println("the last pepole's age is :" + getAge(10));
System.out.println("the binary of the algorism is : " + getBinary(100));
hannota(3, 'a', 'b', 'c');
}
/**
* 第一个人的年龄是10，以后每个人的年龄都比前一个人的年龄大2岁，求第n个人的年龄
*
* @param people
* @return
*/
public static int getAge(int people) {
if (people == 1) {
return 10;
} else {
return 2 + getAge(people - 1);
}
}
/**
* 求一个十进制数字的二进制形式是多少
*
* @param num
* @return
*/
public static String getBinary(int num) {
if (num < 2) {
return num + "";
} else {
return getBinary(num / 2) + num % 2 + "";
}
}

/**
* 写一个方法，要求参数int类型，如：传入一个12345，返回结果54321。用递归
*/
public class Reverse {
public static void reverse(int number) {
if (number < 10) {
System.out.print(number);
} else {
int num = number % 10;
System.out.print(num);
reverse(number / 10);
}
}
public static void main(String[] args) {
reverse(123);
}
}