关于二叉树的非递归遍历实例代码分享

 public void pre_iteration(Node p) {if (p == null) return;
        Stack<Node> stack = new Stack<>();while (!stack.isEmpty() || p != null) {while (p != null) {
                System.out.println(p.val);
                stack.push(p);
                p = p.left;
            }if (!stack.isEmpty()) {
                p = stack.pop();
                p = p.right;
            }
        }
    }

public void in_iteration(Node p) {if (p == null) return;
        Stack<Node> stack = new Stack<>();while (!stack.isEmpty() || p != null) {while (p != null) {
                stack.push(p);
                p = p.left;
            }if (!stack.isEmpty()) {
                p = stack.pop();
                System.out.println(p.val);
                p = p.right;
            }
        }
    }

public static void post_iteration(Node p) {if (p == null) return;
        Stack<Node> stack = new Stack<>();
        Stack<Boolean> stack2 = new Stack<>();while (!stack.isEmpty() || p != null) {while (p != null) {
                stack.push(p);
                stack2.push(false);
                p = p.left;
            }while (!stack.isEmpty() && stack2.peek()) {
                System.out.println(stack.pop().val);
                stack2.pop();
            }if (!stack.isEmpty()) {
                p = stack.peek().right;
                stack2.pop();
                stack2.push(true);
            }
        }
    }