递归三要素：
1、明确递归终止条件；
2、给出递归终止时的处理办法；
3、提取重复的逻辑，缩小问题规模。
1、1+2+3+…+n
import java.util.Scanner;
public class Recursion {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
System.out.println(sum(n));
}
public static int sum(int n) {
if(n == 1) {
return n;
}
else {
return n + sum(n-1);
}
}
}
2、1 * 2 * 3 * … * n
import java.util.Scanner;
public class Recursion {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
System.out.println(multiply(n));
}
public static int multiply(int n) {
if(n == 1) {
return n;
}
else {
return n*multiply(n-1);
}
}
}
3、斐波那契数列
前两项均为1，第三项开始，每一项都等于前两项之和。即：1，1，2，3，5，8，…
import java.util.Scanner;
public class Recursion {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
int n = in.nextInt();
System.out.println(fun(n));
}
public static int fun(int n) {
if (n <= 2) {
return 1;
}
else {
return fun(n-1) + fun(n-2);
}
}
}
4、二叉树的遍历（前、中、后）
import java.util.Arrays;
import java.util.linkedList;
public class MyBinaryTree {
//二叉树节点
private static class TreeNode{
int data;
TreeNode leftChild;
TreeNode rightChile;
public TreeNode(int data) {
this.data = data;
}
}
//构建二叉树
public static TreeNode createBinaryTree(linkedList inputList) {
TreeNode node = null;
if(inputList == null || inputList.isEmpty()) {
return null;
}
Integer data = inputList.removeFirst();
//如果元素为空，则不再递归
if(data != null){
node = new TreeNode(data);
node.leftChild = createBinaryTree(inputList);
node.rightChile = createBinaryTree(inputList);
}
return node;
}
//前序遍历:根节点，左子树，右子树
public static void preOrderTraveral(TreeNode node) {
if (node == null) {
return;
}
System.out.println(node.data);
preOrderTraveral(node.leftChild);
preOrderTraveral(node.rightChile);
}
//中序遍历：左子树，根节点，右子树
public static void inOrderTraveral(TreeNode node) {
if(node == null) {
return;
}
inOrderTraveral(node.leftChild);
System.out.println(node);
inOrderTraveral(node.rightChile);
}
//后序遍历：左子树，右子树，根节点
public static void postOrderTraveral(TreeNode node) {
if (node == null) {
return;
}
postOrderTraveral(node.leftChild);
postOrderTraveral(node.rightChile);
System.out.println(node.data);
}
public static void main(String[] args) {
linkedList inputList = new linkedList(Arrays.asList(new Integer[]{3,2,9,null,null,10,null,null,8,null,4}));
TreeNode treeNode = createBinaryTree(inputList);
System.out.println("前序遍历：");
preOrderTraveral(treeNode);
System.out.println("中序遍历：");
inOrderTraveral(treeNode);
System.out.println("后序遍历：");
postOrderTraveral(treeNode);
}
}
以上就是java递归算法实例的详细内容，大家如果有任何补充的地方可以联系考高分网小编。
