二叉树的先序、中序、后序非递归遍历

先序

 /**
     * 前序遍历
     * 非递归
*/
public void preOrder1(BinaryNode<AnyType> Node)
{
        Stack<BinaryNode> stack = new Stack<>();
        while(Node != null || !stack.empty())
        {
            while(Node != null)
            {
                System.out.print(Node.element + "   ");
                stack.push(Node);
                Node = Node.left;
            }
            if(!stack.empty())
            {
                Node = stack.pop();
                Node = Node.right;
            }
        }
}

中序

/**
 * 中序遍历
 * 非递归
*/
public void midOrder1(BinaryNode<AnyType> Node)
{
    Stack<BinaryNode> stack = new Stack<>();
    while(Node != null || !stack.empty())
    {
        while (Node != null)
        {
            stack.push(Node);
            Node = Node.left;
        }
        if(!stack.empty())
        {
            Node = stack.pop();
            System.out.print(Node.element + "   ");
            Node = Node.right;
        }
    }
}

后序

/**
 * 后序遍历
 * 非递归
 */
public void posOrder1(BinaryNode<AnyType> Node)
{
    Stack<BinaryNode> stack1 = new Stack<>();
    Stack<Integer> stack2 = new Stack<>();
    int i = 1;
    while(Node != null || !stack1.empty())
    {
        while (Node != null)
        {
            stack1.push(Node);
            stack2.push(0);
            Node = Node.left;
        }

        while(!stack1.empty() && stack2.peek() == i)
        {
            stack2.pop();
            System.out.print(stack1.pop().element + "   ");
        }

        if(!stack1.empty())
        {
            stack2.pop();
            stack2.push(1);
            Node = stack1.peek();
            Node = Node.right;
        }
    }
}