递归二叉树的序列打印、非递归二叉树的序列打印

递归二叉树的序列打印 非递归二叉树的序列打印

递归二叉树的序列打印 请用递归方式实现二叉树的先序、中序和后序的遍历打印。 给定一个二叉树的根结点root，请依次返回二叉树的先序，中序和后续遍历(二维数组的形式)。 我的提交

-- coding:utf-8 --

class TreeNode:

def init(self, x):

self.val = x

self.left = None

self.right = None

class TreeToSequence: def convert(self, root): # write code here result = [[], [], []] if not root: return result self.pre(root, result[0]) self.inOrder(root, result[1]) self.afterOrder(root, result[2]) return result

def pre(self, root, result):
    if not root.left and not root.right:
        result.append(root.val)
        return 
    result.append(root.val)
    if root.left:
        self.pre(root.left, result)
    if root.right:
        self.pre(root.right, result)
    return

def inOrder(self,root, result):
    if not root.left and not root.right:
        result.append(root.val)
        return
    if root.left:
        self.inOrder(root.left, result)
    result.append(root.val)
    if root.right:
        self.inOrder(root.right, result)
    return

def afterOrder(self, root, result):
    if not root.left and not root.right:
        result.append(root.val)
        return
    if root.left:
        self.afterOrder(root.left, result)
    if root.right:
        self.afterOrder(root.right, result)
    result.append(root.val)

    return

参考答案 class TreeToSequence { public: void pre(TreeNode* rt,vector &ret){ ret.push_back(rt->val); if(rt->left) pre(rt->left,ret); if(rt->right) pre(rt->right,ret); } void mid(TreeNode* rt,vector &ret){ if(rt->left) mid(rt->left,ret); ret.push_back(rt->val); if(rt->right) mid(rt->right,ret); } void aft(TreeNode* rt,vector &ret){ if(rt->left) aft(rt->left,ret); if(rt->right) aft(rt->right,ret); ret.push_back(rt->val); } vector > convert(TreeNode* root) { vector A,B,C; vector > ret; pre(root,A); mid(root,B); aft(root,C); ret.push_back(A); ret.push_back(B); ret.push_back(C); return ret; } };

非递归二叉树的序列打印 请用非递归方式实现二叉树的先序、中序和后序的遍历打印。 给定一个二叉树的根结点root，请依次返回二叉树的先序，中序和后续遍历(二维数组的形式)。

参考文档：【数据结构与算法】二叉树递归与非递归遍历（附完整源码） http://blog.csdn.net/ns_code/article/details/12977901/

我的提交

-- coding:utf-8 --

class TreeNode:

def init(self, x):

self.val = x

self.left = None

self.right = None

class TreeToSequence: def convert(self, root): # write code here result = [[],[],[]] if not root: return result self.pre(root, result[0]) self.mid(root, result[1]) self.after(root, result[2]) return result

def pre(self, root, result):
    """非递归前序遍历
    """
    if not root:
        return
    stack = []
    stack.append(root)

    while stack:
        node = stack.pop()
        result.append(node.val)
        if node.right:
            stack.append(node.right)
        if node.left:
            stack.append(node.left)

def mid(self, root, result):
    """非递归中序遍历
    """
    def pushLeftChild(root, stack):
        p = root
        while p:
            stack.append(p)
            p = p.left

    stack = []

    pushLeftChild(root, stack)

    while stack:
        node = stack.pop()
        result.append(node.val)
        pushLeftChild(node.right, stack)

    return


def after(self, root, result):
    """非递归后序遍历
    """
    if not root:
        return
    stack1 = []
    stack2 = []
    stack1.append(root)
    while stack1:
        node = stack1.pop()
        stack2.append(node)
        if node.left:
            stack1.append(node.left)
        if node.right:
            stack1.append(node.right)

    while stack2:
        result.append(stack2.pop().val)
    return