排序，数据结构-python

一、几种基本排序算法

1、冒泡

<span style="font-size:18px;"><span style="font-size:18px;">class pop:    def __init__(self,val):        self.val=list(val)    def getpop(self):        val=list(self.val)        for i in range(len(val)-1):            for j in range(i+1,len(val)):                if val[i]>val[j]:                    val[i],val[j]=val[j],val[i]        return valif __name__=="__main__":    p=pop((5,4,3,6,1))    print p.getpop()</span></span>

2、选择

<span style="font-size:18px;">class sel:    def __init__(self,val):        self.val=list(val)    def getsel(self):        a=self.val        for i in range(len(a)-1):            k=i            for j in range(i+1,len(a)):                if a[k]>a[j]:                    k=j            a[k],a[i]=a[i],a[k]        print  aif __name__=="__main__":    s=sel((5,4,3,6,1,7))    s.getsel()</span>

3、插入

<span style="font-size:18px;">class inst:    def __init__(self,val):        self.val=list(val)    def getinst(self):        val=self.val        for i in range(1,len(val)):            j=i-1            while j>=0 and val[j]>val[i]:                val[i],val[j]=val[j],val[i]                j-=1                i-=1        print valif __name__=="__main__":    ins=inst((5,4,3,6,7,1))    ins.getinst()</span>

4、快排

<span style="font-size:18px;">import randomdef QuickSort(num):    if len(num)<=1:        return num    greater=[]    less=[]    p=num.pop(random.randint(0,len(num)-1))    for item in num:        if item < p:            less.append(item)        else:            greater.append(item)    return QuickSort(less)+[p]+QuickSort(greater)print QuickSort([5,4,3,6,7])</span>

5、归并

<span style="font-size:18px;">def MergerSort(num):    if len(num)<=1:        return num    left=MergerSort(num[:len(num)/2])    right=MergerSort(num[len(num)/2:])    print left    print right    result=[]    while len(left)>0 and len(right)>0:        if left[0]>right[0]:            result.append(right.pop(0))        else:            result.append(left.pop(0))    if len(left)>0:        result.extend(MergerSort(left))    else:        result.extend(MergerSort(right))    return resultMergerSort([5,4,3,6,1,7])</span>

二、数据结构

1、树（前序遍历、中序遍历、后序遍历）

<span style="font-size:18px;"># -*- coding: utf-8 -*-class Treenode:    def __init__(self):        self.val='*'        self.left=None        self.right=Noneclass Tree:    def create_tree(self,treenode):        data=raw_input('输入结点值：')        if data=='*':treenode=None        else:            treenode.val=data            treenode.left=Treenode()            self.create_tree(treenode.left)            treenode.right=Treenode()            self.create_tree(treenode.right)    def visit(self,treenode):        if treenode is not '*':            print str(treenode.val)+'\t',    def pre(self,treenode):        if treenode is not None:            self.visit(treenode)            self.pre(treenode.left)            self.pre(treenode.right)    def mid(self,treenode):        if treenode is not None:            self.mid(treenode.left)            self.visit(treenode)            self.mid(treenode.right)    def post(self,treenode):        if treenode is not None:            self.post(treenode.left)            self.post(treenode.right)            self.visit(treenode)if __name__=="__main__":    t=Treenode()    tree=Tree()    tree.create_tree(t)    tree.pre(t)    print '\n'    tree.mid(t)    print '\n'    tree.post(t)</span>

由前序遍历+中序遍历重建二叉树：

<span style="font-size:18px;">class  Node:    def __init__(self,val):        self.val=val        self.left=None        self.right=Noneclass retree:    def rebulid(self,pre,mid):        pre=list(pre)        mid=list(mid)        if not pre or not mid:return        root=Node(pre[0])        i=mid.index(root.val)        root.left=self.rebulid(pre[1:i+1],mid[:i])        root.right=self.rebulid(pre[i+1:],mid[i+1:])        return rootif __name__=="__main__":    a=[5,4,3,6,1,7]    b=[3,4,5,1,7,6]    test=retree()    n=test.rebulid(a,b)   </span>

2、链表（遍历）

<span style="font-size:18px;">class Node:    def __init__(self):        self.val='*'        self.next=Noneclass List:    def create_list(self,node):        data=raw_input('please input some numbers: \n')        if data=='*':            node=None        else :            node.val=data            node.next=Node()            self.create_list(node.next)    def get_list(self,node):        while( node is not None):            print node.val            node=node.nextif __name__=="__main__":    t=Node()    ls=List()    ls.create_list(t)    ls.get_list(t)</span>

链表的全部：

<span style="font-size:18px;">#!/usr/bin/python# -*- coding: utf-8 -*-class Node(object):    def __init__(self,val,p=0):        self.data = val        self.next = pclass LinkList(object):    def __init__(self):        self.head = 0    def __getitem__(self, key):        if self.is_empty():            print 'linklist is empty.'            return        elif key <0  or key > self.getlength():            print 'the given key is error'            return        else:            return self.getitem(key)    def __setitem__(self, key, value):        if self.is_empty():            print 'linklist is empty.'            return        elif key <0  or key > self.getlength():            print 'the given key is error'            return        else:            self.delete(key)            return self.insert(key)    def initlist(self,data):        self.head = Node(data[0])        p = self.head        for i in data[1:]:            node = Node(i)            p.next = node            p = p.next    def getlength(self):        p =  self.head        length = 0        while p!=0:            length+=1            p = p.next        return length    def is_empty(self):        if self.getlength() ==0:            return True        else:            return False    def clear(self):        self.head = 0    def append(self,item):        q = Node(item)        if self.head ==0:            self.head = q        else:            p = self.head            while p.next!=0:                p = p.next            p.next = q    def getitem(self,index):        if self.is_empty():            print 'Linklist is empty.'            return        j = 0        p = self.head        while p.next!=0 and j <index:            p = p.next            j+=1        if j ==index:            return p.data        else:            print 'target is not exist!'    def insert(self,index,item):        if self.is_empty() or index<0 or index >self.getlength():            print 'Linklist is empty.'            return        if index ==0:            q = Node(item,self.head)            self.head = q        p = self.head        post  = self.head        j = 0        while p.next!=0 and j<index:            post = p            p = p.next            j+=1        if index ==j:            q = Node(item,p)            post.next = q            q.next = p    def delete(self,index):        if self.is_empty() or index<0 or index >self.getlength():            print 'Linklist is empty.'            return        if index ==0:            q = Node(item,self.head)            self.head = q        p = self.head        post  = self.head        j = 0        while p.next!=0 and j<index:            post = p            p = p.next            j+=1        if index ==j:            post.next = p.next    def index(self,value):        if self.is_empty():            print 'Linklist is empty.'            return        p = self.head        i = 0        while p.next!=0 and not p.data ==value:            p = p.next            i+=1        if p.data == value:            return i        else:            return -1l = LinkList()l.initlist([1,2,3,4,5])print l.getitem(4)l.append(6)print l.getitem(5)l.insert(4,40)print l.getitem(3)print l.getitem(4)print l.getitem(5)l.delete(5)print l.getitem(5)l.index(5)</span>