二叉树前中后递归遍历

public class Node {
    public int value;
    public Node left;
    public Node right;

    public Node (int data){
        this.value = data;
    }
}

public class BinaryTreeMethod {

    /**
     * 二叉树递归前序遍历
     * @param head
     */
    public void preOrderRecur(Node head){
        if(head == null){
            return;
        }
        System.out.print(head.value + " ");
        preOrderRecur(head.left);
        preOrderRecur(head.right);
    }

    /**
     * 二叉树递归中序遍历
     * @param head
     */
    public void inOrderRecur(Node head){
        if(head == null){
            return;
        }
        inOrderRecur(head.left);
        System.out.print(head.value + " ");
        inOrderRecur(head.right);
    }

    /**
     * 二叉树递归后序遍历
     * @param head
     */
    public void postOrderRecur(Node head){
        if(head == null){
            return;
        }
        postOrderRecur(head.left);
        postOrderRecur(head.right);
        System.out.print(head.value + " ");
    }
}

测试代码:

public class Test {

    public  static void  main(String[] args){
        Node head = new Node(3);
        Node left = new Node(5);
        Node right = new Node(2);
        head.left = left;
        head.right = right;

        left.left = new Node(1);
        right.left = new Node(7);

        BinaryTreeMethod method = new BinaryTreeMethod();
        method.preOrderRecur(head);
        System.out.println();
        method.inOrderRecur(head);
        System.out.println();
        method.postOrderRecur(head);
    }
}