二叉树的一些操作的代码实现

class TreeNode:    def __init__(self, x):        self.val = x        self.left = None        sele.right = None

较为直观的打印二叉树

def printTree(root):    if not root:        return    print("Binary Tree: ")    printInOrder(root, 0, 'H', 10)def printInOrder(root, height, preStr, length):    if not root:        return    printInOrder(root.right, height+1, 'v', length)    string = preStr + root.val + preStr    leftLen = (length - len(string)) // 2    rightLen = length - len(string)- leftLen    res = " "*leftLen + string + " "*rightLen    print(" "*height*length + res)    printInOrder(root.left, height+1, '^', length)

计算树的深度

def getDepth(root):    if not root:        return 0    return 1 + max(getDepth(root.left), getDepth(root.right))

计算树的带权路径长度

def getWPL(root, depth=0):    if not root:        return 0    if not root.left and not root.right:        return depth * int(root.val)    return getWPL(root.left, depth + 1) + getWPL(root.right, depth + 1)

打印二叉树的边界节点

给定一棵二叉树的头节点，按照如下两种标准分别实现二叉树边界节点的逆时针打印。
标准一：

1. 头节点为边界节点
2. 叶节点为边界节点
3. 如果节点在其所在层中的最左边或最右边，那么也是边界节点

标准二：

1. 头节点为边界节点
2. 叶节点为边界节点
3. 树左边界延伸下去的路径为边界节点
4. 树右边界延伸下去的路径为边界节点

#标准一def printEdge1(root):    def getHeight(root, height=0):        if not root:            return 0        return max(getHeight(root.left, height+1), getHeight(root.right, height+1)) + 1    def getMap(root, i, map):        if not root:            return        if map[i][0] == None:            map[i][0] = root        map[i][1] = root        getMap(root.left, i+1, map)        getMap(root.right, i+1, map)    def printLeafNotInMap(root, i, map):        if not root:            return        if not root.left and not root.right and root != map[i][0] and \                root != map[i][1]:            print(root.val, end=' ')        printLeafNotInMap(root.left, i+1, map)        printLeafNotInMap(root.right, i+1, map)    if not root:        return    height = getHeight(root)    map = [[None for i in range(2)] for j in range(height)]    getMap(root, 0, map)    for i in range(len(map)):        print(map[i][0].val, end=' ')    printLeafNotInMap(root, 0, map)    for i in range(len(map)-1, -1, -1):        if map[i][0] != map[i][1]:            print(map[i][1].val, end=' ')

#标准二def printEdge2(root):    def printLeft(root, isPrint):        if not root:            return        if isPrint or (root.left == None and root.right == None):            print(root.val, end=' ')        printLeft(root.left, isPrint)        printLeft(root.right, bool(isPrint and root.left == None))    def printRight(root, isPrint):        if not root:            return        printRight(root.left, bool(isPrint and root.right == None))        printRight(root.right, isPrint)        if isPrint or (root.left == None and root.right == None):            print(root.val, end=' ')    if not root:        return    print(root.val, end=' ')    if root.left and root.right:        printLeft(root.left, True)        printRight(root.right, True)    elif root.left:        printEdge2(root.left)    elif root.right:        printEdge2(root.right)

二叉树的序列化和反序列化

说明：二叉树被记录成文件的过程叫作二叉树的序列化，通过文件内容重建原来二叉树的过程叫作二叉树的反序列化

#二叉树的序列化和反序列化（先序）def serialByPre(root):    if not root:        return '#!'    res = root.val + '!'    res += serialByPre(root.left)    res += serialByPre(root.right)    return resdef reconByPreString(preStr):    def reconPreOrder(values):        key = values.pop(0)        if key == '#':            return None        root = TreeNode(key)        root.left = reconPreOrder(values)        root.right = reconPreOrder(values)        return root    values = preStr.split('!')    return reconPreOrder(values)

#二叉树的序列化和反序列化（层次）def serialByLevel(root):    if root == '#':        return '#!'    stack = []    stack.append(root)    res = root.val + '!'    while stack:        root = stack.pop()        if root.left:            res += root.left.val + '!'            stack.append(root.left)        else:            res += '#!'        if root.right:            res += root.right.val + '!'            stack.append(root.right)        else:            res += '#!'    return resdef reconByLevelString(levStr):    def generateNode(key):        if key == '#':            return None        return TreeNode(key)    values = levStr.split('!')    head = generateNode(values.pop(0))    queue = []    if head:        queue.append(head)    while queue:        root = queue.pop(0)        root.left = generateNode(values.pop(0))        root.right = generateNode(values.pop(0))        if root.left:            queue.append(root.left)        if root.right:            queue.append(root.right)    return head