常见的面试题整理

在这里插入代码片
#二分查找def binarySearch(alist, item):first=0;last=len(alist)-1;while first <= last:mid=(first+last)/2;print(mid)if alist[mid]>item:last=mid-1;elif alist[mid]<item:first=mid+1return -1test=[0,1,2,8,13,17,19,9,0]print(binarySearch(test,3))#冒泡排序
def bubbleSort(alist):for passnum in range(len(alist)-1,0,-1):for i in range(passnum)if alist[i]>alist[i+1]:alist[i],alist[i+1]=alist[i+1],alist[i]return alist#插入排序def insertionSort(alist):for index in range(1,len(alist)):currentValue=alist[index]position=indexwhile position>0 and alist[position-1]>currentValue:alist[position]=alist[position-1]position-=1alist[position]=currentValue#快速排序
def quickSort(alist):quickSortHelper(alist,0,len(alist)-1)def quickSortHelper(alist,first,last):if first<last:splitPoint=partition(alist,first,last)quickSortHelper(alist,first,splitPoint-1)quickSortHelper(alist,splitPoint+1,last)def partition(alist,first,last)item=alist[first]left=first+1right=lastwhile left<right:while alist[left]<=item and left<=rightleft +=1alist[left],alist[right]=alist[right],alist[left]while alist[right]>=item and left<=right:right -=1alist[left],alist[right]=alist[right],alist[left]return right#return left#树的四种遍历
class node(object):def __init__(self,data=None,left=None,right=None):self.data=dataself.left=leftself.right=right#深度def depth(tree):if tree== None:return 0left,right=depth(tree.left),depth(tree.right)return max(left,right)+1#前序遍历def pre_order(tree):if tree==None:returnprint tree.datapre_order(tree.left)pre_order(tree.right)#中序遍历def min_order(tree):if tree== None:returnmin_order(tree.left)print(tree.data)min_order(tree.right)#后序遍历def post_order(tree):if tree==Nonereturnpost_order(tree.left)post_order(tree.right)print(tree.data)#层次遍历def level_order(tree):if tree==Nonereturnq=[]q.append(tree)while q:current=q.pop(0)print current.dataif current.left != None:q.append(current.left)if current.right !=None:q.append(current.right)#括号匹配
def match_parentTheses(s):ls=[]parentTheses="()[]{}"for i in range(len(s)):si=s[i]if parentTheses.find(si) == -1:continueif si == "(" or si=="{" or si=="[":ls.append(si)continueif len(ls)==0:return Falsep=ls.pop()if (p == '(' and si == ')') or (p == '[' and si == ']') or (p == '{' and si == '}'):continueelse:return Falseif len(ls)>0:return Falsereturn True#反转链表
def ReverseList(self,pHead):if not pHead or not pHead.next:return pHeadlast=Nonewhile pHead:tmp=pHead.nextpHead.next=lastlast=pHeadpHead=tmpreturn last#链表是否有环
def hasCycle(self,head):flag=Falseif head is None or head.next is None or head.next.next is None:return flag#对slow，fast进行初始化fast = head.next.nextslow=head.nextwhile fast is not slow:if fast.next is None or fast.next.next is None:return flagfast=fast.next.nextslow=slow.nextif fast is slow:flag=Truereturn flagif __name__=='__main__'pass#归并排序
def merge(L,R):n=len(L)+len(R)L.append(float("inf"))R.append(float("inf"))i=0j=0A=[]for k in range(0,n):if(L[i]<R[j])A.append(L[i])i=i+1else:A.append(R[j])j=j+1return A
merge([1,5,6],[2,3])    
def merge_sort(A)l=len(A)if l<=1:return Aelse:mid=l/2print midleft=merge_sort(A[0:mid])right=merge_sort(A[mid:])return merge(left,right)merge_sort([3,2,1,0,5,8,7,2,-5,9,6,11])#改写归并排序
def merge(left,right):res=[]while left and right:min_val=left.pop(0) if left[0] < right[0] else right.pop(0)res.append(min.val)res += left if left else rightreturn resdef merge_sort(A):if len(A)<=1:res=Aelse:mid=len(A)/2left,right=merge_sort(A[:mid]),merge_sort(A[mid:])res=merge(left,right)return res

动态规划：https://blog.csdn.net/zichen_ziqi/article/details/82184495
1、硬币问题

2、爬楼梯问题（青蛙跳台问题）

3、装箱问题与背包问题

4、最大递增子序列问题（最长上升子序列问题）

5、最长公共子序列问题

6、最长公共子串问题

7、最大连续子序列求和问题（最大子串求和问题）

8、股票收益最大化（一次交易、多次交易与最多两次交易）