阶乘：
要求：给定一个数值，计算出它的阶乘值，例如5的阶乘为5*4*3*2*1
实现：
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<span > // 利用递归实现一个数的阶乘值 private static BigDecimal getNum(BigDecimal inNum) { if (inNum.compareTo(BigDecimal.ONE) == 0) { return inNum; } return inNum.multiply(getNum(inNum.subtract(BigDecimal.ONE))); }</span>
（2）Fibonacci数列：1，1，2，3，5，8，13……
要求：找出数列中指定index位置的数值
实现：
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<span > // 利用递归实现了Fibonacci数列 private static int fab(int index) { if (index == 1 || index == 2) { return 1; } else { return fab(index - 1) + fab(index - 2); } }</span>
（3）汉诺塔
要求：汉诺塔挪动
实现：
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<span > <span > </span>private static final String DISK_B = "diskB"; <span > </span>private static final String DISK_C = "diskC"; <span > </span>private static final String DISK_A = "diskA"; <span > </span>static String from=DISK_A; <span > </span> static String to=DISK_C; <span > </span> static String mid=DISK_B; <span > </span> public static void main(String[] args) { <span > </span> String input=JOptionPane.showInputDialog("please input the number of the disks you want me move."); <span > </span> int num=Integer.parseInt(input); <span > </span> move(num,from,mid,to); <span > </span> }</span>
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<span > // 利用递归实现汉诺塔 private static void move(int num, String from2, String mid2, String to2) { if (num == 1) { System.out.println("move disk 1 from " + from2 + " to " + to2); } else { move(num - 1, from2, to2, mid2); System.out.println("move disk " + num + " from " + from2 + " to " + to2); move(num - 1, mid2, from2, to2); } }</span>
（4）排列组合
要求：将输入的一个字符串中的所有元素进行排序并输出，例如：你给出的参数是"abc"，
则程序会输出
abc
acb
bac
bca
cab
cba
实现：
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<span ><span > </span>public static void permute(String str) { <span > </span> char[] strArray = str.toCharArray(); <span > </span> permute(strArray, 0, strArray.length - 1); <span > </span>}</span>
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<span > // 利用递归实现，将输入的一个字符串中的所有元素进行排序并输出 public static void permute(char[] list, int low, int high) { int i; if (low == high) { String cout = ""; for (i = 0; i <= high; i++) { cout += list[i]; } System.out.println(cout); } else { for (i = low; i <= high; i++) { char temp = list[low]; list[low] = list[i]; list[i] = temp; permute(list, low + 1, high); temp = list[low];
标签：java,递归,算法
