python-数据结构代码 树数据结构（树的遍历）

#列表表示树
def BinaryTree(r):
    return [r, [], []]

def insertLeft(root,newBranch):
    t = root.pop(1)
    if len(t) > 1:
        root.insert(1,[newBranch,t,[]])
    else:
        root.insert(1,[newBranch, [], []])
    return root

def insertRight(root,newBranch):
    t=root.pop(2)
    if len(t)>1:
        root.insert(2,[newBranch,[],t])
    else:
        root.insert(2,[newBranch,[],[]])
    return root

def getRootVal(root):
    return root[0]

def setRootVal(root,newVal):
    root[0]=newVal

def getLeftChild(root):
    return root[1]

def getRightChild(root):
    return root[2]

#节点表示树
class BinaryTree:
    def __init__(self,rootObj):
        self.key=rootObj
        self.leftChild=None
        self.rightChild=None

    def insertLeft(self,newNode):
        if self.leftChild==None:
            self.leftChild=BinaryTree(newNode)
        else:
            t=BinaryTree(newNode)
            t.leftChild=self.leftChild
            self.leftChild=t

    def insertRight(self,newNode):
        if self.rightChild == None:
            self.rightChild = BinaryTree(newNode)
        else:
            t = BinaryTree(newNode)
            t.rightChild = self.rightChild
            self.rightChild = t

    def getRightChild(self):
        return self.rightChild

    def getLeftChild(self):
        return self.leftChild

    def setRootVal(self,obj):
        self.key = obj

    def getRootVal(self):
        return self.key

    def preorder(self):
        print(self.key)
        if self.leftChild:
            self.leftChild.preorder()
        if self.rightChild:
            self.rightChild.preorder()

r = BinaryTree('a')
print(r.getRootVal())
print(r.getLeftChild())
r.insertLeft('b')
print(r.getLeftChild())
print(r.getLeftChild().getRootVal())
r.insertRight('c')
print(r.getRightChild())
print(r.getRightChild().getRootVal())
r.getRightChild().setRootVal('hello')
print(r.getRightChild().getRootVal())
print('+++++++++++++++++++++++')

from pythonds.basic.stack import Stack
from pythonds.trees.binaryTree import BinaryTree

def buildParseTree(fpexp):
    fplist=fpexp.split()
    pStack=Stack()
    eTree=BinaryTree('')
    pStack.push(eTree)
    currentTree=eTree
    for i in fplist:
        if i=='(':
            currentTree.insertLeft('')
            pStack.push(currentTree)
            currentTree=currentTree.getLeftChild()
        elif i not in ['+','-','*','/',')']:
            currentTree.setRootVal(int(i))
            parent=pStack.pop()
            currentTree=parent
        elif i in ['+','-','*','/']:
            currentTree.setRootVal(i)
            currentTree.insertRight('')
            pStack.push(currentTree)
            currentTree=currentTree.getRightChild()
        elif i ==')':
            currentTree=pStack.pop()
        else:
            raise ValueError
    return eTree
pt = buildParseTree("( ( 10 + 5 ) * 3 )")
print(pt)
pt.postorder()

def evaluate(parseTree):
    opers={'+':operator.add,'-':operator.sub,'*':operator.mul,'/':operator.truediv}
    leftC=parseTree.getLeftChild()
    rightC=parseTree.getRightChild()
    if leftC and rightC:
        fn = opers[parseTree.getRootVal()]
        return fn(evaluate(leftC),evaluate(rightC))
    else:
        return parseTree.getRootVal()
    
def preorder(tree):
    if tree:
        print(tree.getRootVal())
        preorder(tree.getLeftChild())
        preorder(tree.getRightChild())

def postorder(tree):
    if tree!= None:
        postorder(tree.getLeftChild())
        postorder(tree.getRightChild())
        print(tree.getRootVal())

def postordereval(tree):
    opers={'+':operator.add,'-':operator.sub,'*':operator.mul,'/':operator.truediv}
    res1=None
    res2=None
    if tree:
        res1=postordereval(tree.getLeftChild())
        res2=postordereval(tree.getRightChild())
        if res1 and res2:
            return opers[tree.getRootVal()](res1,res2)
        else:
            return tree.getRootVal()

def inorder(tree):
    if tree != None:
        inorder(tree.getLeftChild())
        print(tree.getRootVal())
        inorder(tree.getRightChild())

def printexp(tree):
    sVal=""
    if tree:
        sVal='(' + printexp(tree.getLeftChild())
        sVal=sVal + str(tree.getRootVal())
        sVal=sVal+printexp(tree.getRightChild())+')'
    return sVal