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"Python Learning notes-data structures and algorithms" bubble sorting Bubble sort

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

Python data structures and algorithms--stacks

= 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

Python Learning notes-data structures and algorithms (i)

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

Python Basics: Lists, dictionaries, tuples, methods for collecting four of data structures, and using collation

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

Basic content of Python data structures

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

Python Common data structures

', ' 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

Python Cookbook-1-Data structures and algorithms

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

Python built-in data structures

, 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

Learn some Python basics-data structures, algorithms, design patterns---visitor patterns

(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

Data structures for Python: Methods in Strings

(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

Python implements bucket ordering of data structures and algorithms

Bucket sortBarrel sequencing has been used since the 1956, and the basic idea of the algorithm is proposed by E.J.ISSAC and R.c.singleton.This algorithm is like having 11 barrels, numbered from 0~10. Each occurrence of a number, in the corresponding number of buckets put aA little flag, and then just count the few small flags in each bucket OK. For example, there are 1 small flags in bucket 2nd, indicating2 appeared once, and in the 3rd barrels there were 1 small flags, indicating that 3 appeare

Collation of several data structures in Python, lists, dictionaries, tuples, collections

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 ', '

Number types of Python data structures

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)

Python data structures and algorithms learn the second day of "time complexity and large o notation"

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

Stack of Python data structures

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

A dictionary of Python data structures

. 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

Python Data structures: lists, tuples, and dictionaries

There are three built-in data structures in Python-lists, tuple tuples, and dictionary DictItems in the list are included in square brackets , and items are separated by commasTuples and lists are very similar, except that tuples and strings are immutable , meaning that you cannot modify tuples. Tuples are defined by a comma-separated list of items in parentheses

---Study on the Road (a) Python data structures and Algorithms (2)-bubble sort, select sort, insert sort

Optimal time complexity: O (n) (in ascending order, sequence already in ascending state) Worst time complexity: O (n2) Stability: Stable Code:"" "Insert sort Time complexity: O (n*n) Stability: Stable" "" "" Import randomimport timedef Insert_sort (list): n = len (list) # from the second position start inserting subscript 1 for J in Range (1,n): # Start comparison from the first J element if it is less than the previous element, the interchange position for

Python data structures and Algorithms Nineth Day "select Sort"

1. Select the principle of sorting2. Code implementationdefSelection_sort (alist): N=Len (alist)#requires a n-1 selection operation forIinchRange (n-1): #Record minimum positionMin_index =I#Select the minimum data from the i+1 position to the end forJinchRange (i+1, N):ifALIST[J] Alist[min_index]: Min_index=J#If the selected data is not in the correct location, swap ifMin_index! =I

"Python coolbook" Data Structures and Algorithms _ Dictionary comparison & Dictionaries and collections

, intersection, and difference operations. So, if you want to perform some normal collection operations on the keys of the collection, you can use the key view objects directly without first converting them to a set.The dictionary's items () method returns an element view object that contains (key, value) pairs. This object also supports collection operations and can be used to find out which two dictionaries have the same key-value pairs.Although the values () method of the dictionary is simila

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