python data structures book

first 1frequency = [0 forIinchRange (0, 10, 1)] I= 1#do factorial operations, from 1! , 2! , 3! , until 100! The Operation forNinchRange (1, 100, 1): I= n *i m=First_number (i) frequency[m]= Frequency[m] + 1PrintFrequencyResults:/users/liudaoqiang/pycharmprojects/numpy/venv/bin/python/users/liudaoqiang/project/python_project/bat_day17/ 7, 7, 7, 3, ten, 4]process finished with exit code 03. Ben Ford's Law:In life, the probability of the first dig

included.Realpath=[]#only the true path to the end is recorded . whileCurnode[2]!=-1:#as long as it wasn't the first oneRealpath.append (curnode[0:2]) Curnode=PATH[CURNODE[2]]#keep looking for the nextRealpath.append (Curnode[0:2])#get the last source .Realpath.reverse ()Print(Realpath)defMap_path (x1,y1,x2,y2): Queue=deque () path=[]#Create a list record pathQueue.append ((x1,y1,-1))#-1 is set for path source search whileLen (queue) >0:curnode=Queue.popleft () path.append (Curnode)ifCu

-operation Traversal, we first recursively use the post-traversal to access the Saozi right subtree, the last access to the root node root node, right subtree, left dial hand tree def postorder (self, Root): "" " recursive implementation of subsequent traversal" " if root = = None: return self.postorder (root.lchild) Self.postorder (root.rchild) print (Root.elem)Breadth-first traversal (hierarchical traversal)From the root of the tree, from top to bottom, from l

Original address: Http://docs.pythontab.com/python/python3.4/datastructures.html#tut-tuplesThe best way to understand a dictionary is to think of it as an unordered key: a set of value pairs (Key:value pairs) whose keys must be distinct (within the same dictionary).A pair of curly braces creates an empty dictionary: {} .>>> Tel = {'Jack': 4098,'Sape': 4139}>>> tel['Guido'] = 4127>>>tel{'Sape': 4139,'Guido': 4127,'Jack': 4098}>>> tel['Jack']4098>>>delt

Recommend a Visual Web site "Visual Algo": Url= ' https://visualgo.net/en/sorting 'This website gives the principles and processes of various sorting algorithms, which are visualized through dynamic forms. The related pseudo-code are also given, as well as the specific steps to execute to code."Bubble Sort"You need to repeatedly visit the sequence of columns that need to be sorted. The size of the adjacent two items is compared during the visit, and if the order is not correct, two items are exc

= mid#determine the starting subscript for the post-half string - Else: -Next = mid + 1 the -top = Mid-1 - forIinchRange (Next,len (A)): - ifStack[top]! =A[i]: + returnFalse -Top-= 1 + A returnTrueTest:if __name__= ="__main__" := List ("Hahahahahahahahaha ") print is_plalindrome_demo1 (q)Manual implementation Stack1 #simple filo stack category2 classStack:3 def __init__(self):4Self.top = None#point to top of stack5Self.end = None#Point to the bo

does not support the comparison size.-priority the priority counter, ensuring that the smallest element function in the queue (the most important) is always placed in _queue[0]. heapq.heappush()and the first element is heapq.heappop() inserted and deleted separately on the queue, the _queue first element of the _queue is always the smallest, ensuring that the queue _queue the first element with the highest priority.Reference: "Python Cookbook" 3rd Ed

, card): Table.append (Card)ifTable.count (Card) >=2: whileTable.count (Card) >0:person.append (Table.pop ()) whileLen (hen)!=0 andLen (haa)! =0:#print "tab:", List (table)i = Hen.popleft ()#hen the cards first#print "Hen put", IRefreshtable (hen, i)#Hen Action#print "hen:", List (hen) #print "tab:", List (table)j = Haa.popleft ()#Haa after the card#print "Haa put", JRefreshtable (Haa, J)#haa Action#print "Haa:", List (HAA)#print "tab:", List (table)#print "Next Turn"

in a dictionaryThe Dict () constructor can create a dictionary directly from the key-value pairDict ([' Tim ', 123), (' Tiny ', 234)]) >>>{' Tiny ': 234, ' Tim ': 123}Derivation creates a dictionary:{d2:d2+ ' @main. com ' for D2 in List (D.keys ()}}>>>{' Jack ': ' [email protected] ', ' Tom ': ' [email protected] '}Exercise: A key-value pair in a circular output dictionary:For Name,email in D.items ():Print (Name,email)4. CollectionEmpty collection: A = set () ※ to create an empty collection, y

a queue.List Deduction formula:>>> vec=[2,4,6]>>> [3*x forXinchVEC] [6, 12, 18]>>> [[X,x**2] forXinchVEC] [[2, 4], [4, 16], [6, 36]]>>> [3*x forXinchVecifX>3][12, 18]>>> [3*x forXinchVecifX][]>>> vec1=[2,4,6]>>> vec2=[4,3,-9]>>> [X*y forXinchVec1 forYinchVEC2] [8, 6,-18, 16, 12,-36, 24, 18, 54]>>> [Vec1[i]*vec2[i] forIinchRange (len (VEC1))] [8, 12, 54]>>> [Str (Round (355/113,i)) forIinchRange (1,6)]#round (x,i) returns the rounding value of the floating-point number x, preserving the decimal

', ' Y ': ' 2 '}, {' X ': ' 3 ', ' Y ': ' 3 '}, {' X ': ' 4 ', ' Y ': ' 4 '}]One-to-one lambda expressions>>> p = [{' X ': ' 3 ', ' Y ': ' 3 '},{' x ': ' 4 ', ' Y ': ' 4 '},{' x ': ' 2 ', ' Y ': ' 2 '},{' x ': ' 1 ', ' y ': ' 1 '}]>>> plamb = [n[' x '] > ' 2 ' for n in P]>>> Print (PLAMB)[True, True, False, false]The compress is used in conjunction with 11 items.>>> from Itertools Import compress>>> list (compress (P,PLAMB))[{' X ': ' 3 ', ' Y ': ' 3 '}, {' X ': ' 4 ', ' Y ': ' 4 '}]13. Logical

1 Sequence decompression: through * to pass the match*a, B = somelist, First, *mid, last = Somelist, a, *b = Somelist2 using bidirectional queues: From collections import dequeQ = deque (maxlen=5) can be fixed lengthQ = deque () can also be any lengthcan be inserted and removed from both ends, append, Appendleft, pop, popleft3 finding the largest or smallest n elements: using heapq (heap queue)HEAPQ. nlargest (N, Alist) heapq. nsmallest (n, alist) is suitable when n is relatively smallYou can al

, 3), (1, 4), (2, 3), (2, 1), (2, 4), (3, 1), (3, 4)] For a more advanced application, consider the following 3x4 matrix consisting of three 4-length lists:1 >>> matrix = [2 ... [1, 2, 3, 4], 3 ... [5, 6, 7, 8], 4 ... [9, ten, one, one], 5 ...]The following list resolution allows you to transpose the matrix:1 >>> [[Row[i] for in matrix] for in Range (4)] 2 [[1, 5, 9], [2, 6, 10], [3, 7, 11], [4, 8, 12]]It is parsed from the outermost layer, that is, the function of the above code

(self) self.engine.accept (visitor) self.body.accept (Visito R) forWheelinchself.wheels:wheel.accept (visitor)#This is our visitor, and every change is here .classPrintvisitor:defVisitwheel (self, Wheel):Print "Visiting"+wheel.name+"Wheel" defVisitengine (self, Engine):Print "Visiting engine" defvisitbody (self, body):Print "Visiting Body" defVisitcar (self, car):Print "Visiting Car"if __name__=='__main__': Car=Car () visitor=printvisitor () car.accept (visitor)Learn some

(from,to) mapping table, encoding and decoding when used for example: Maptable=string.maketrans (' 123 ', ' abc ') s= ' 111abc123abc ' Print S.translate (maptable) results:aaaabcabcabc Nine, numeric type conversion int () float () long () import string1, String.atoi (s,a) can also convert octal, Hexadecimal A: Represents the number of s= ' + ' print int (s) print string.atoi (s) Result: 1818print string.atoi (' 011 ', 8) 9print string.atoi (' 0x11 ', 16) 172, String.atol (' 11 ') 113, String.at

pairDict ([' Tim ', 123), (' Tiny ', 234)]) >>>{' Tiny ': 234, ' Tim ': 123}Derivation creates a dictionary:{d2:d2+ ' @main. com ' for D2 in List (D.keys ()}}>>>{' Jack ': ' [email protected] ', ' Tom ': ' [email protected] '}Exercise: A key-value pair in a circular output dictionary:For Name,email in D.items ():Print (Name,email)4. CollectionEmpty collection: A = set () ※ to create an empty collection, you must use Set ()Demonstrate:Basket = {' Apple ', ' orange ', ' apple '} >>>{' orange ', '

the x in parentheses to a floating-point type;Complex (x) converts the x in parentheses into a complex number;For example:---------------Convert 666 of string types to integer----------------------->>>Print(Type (int ("666")))class 'int'>---------------Convert 666 of string types to floating-point--------------------->>>Print(Type (float ("666")))class 'float'>>>>Print(Float ("666"))666.0--------------Convert 666 of string types to plural------------------------>>>Print(Complex ("666"))(666+0J)

algorithm is executed on different computers, and the execution time is not the same.Therefore, the operational efficiency should be related to the execution steps, which will be the time complexity of the execution steps.In the first algorithm: T (n) = n^3 * 2In the second algorithm: T (n) = n^2 * 3If the system and bias items are not considered, then the progressive function, using the progressive function representation, is the large O notation:In the first algorithm: T (n) = O (n^3)In the s

StackStack, which is called a stack, is a container that can be stored in data elements, access elements, delete elements, and it is characterized only by allowing the addition of data (English: Push) and output data (English: Pop) to one end of the container (called the stack Top indicator, English: top). Without a location concept, it is guaranteed that any ele

. 3Update: The parameter is key and value, regardless of whether the key exists, it becomes the form of Key:value. Delete (not used in work) fruits{'a':'appleupdate','b':'Banana','g':'Grape','o':'Orange','Martin': -,3:5}fruits.pop (3)5fruits{'a':'appleupdate','b':'Banana','g':'Grape','o':'Orange','Martin': -} change:1, Assignment2, updatea{2:9,3:5,4:9}a[0] =8a{2:9,3:5,4:9,0:8}a[2] =8a{2:8,3:5,4:9,0:8}a.update ({3:Ten}) a{2:8,3:Ten,4:9,0:8} check a{2:8,3:Ten,4:9,0:8}a.get (2)8a[0]8two different v