Basics
Learn about Python operators, Python data types, and Python functions, which are all important parts of this flexible programming language. Python is one of the preferred languages among coders for most of the competitive programming challenges. Most of the problems are easily computed in a reasonable time frame using python. For some of the complex problem, writing fast-enough python code is often a challenge.
| Print a number | print(123) |
| Print a string | print('test') |
| Adding numbers | print(1+2) |
| Variable assignment | number = 123 |
| Print a variable | print(number) |
| Function call | x = min(1, 2) |
| Comment | # a comment |
Types
| Integer | 42 |
| String | 'a string' |
| List | [1, 2, 3] |
| Tuple | (1, 2, 3) |
| Boolean | True |
Useful functions
Competitive Programming in Python: 128 Algorithms to Develop Your Coding Skills Free PDF Learn to write DAX: a practical guide to learning Power Pivot for Excel and Power BI Python Machine Learning: The Complete Guide to Understand Python Machine Learning for Beginners and Artificial Intelligence.
| Write to the screen | print('hi') |
| Calculate length | len('test') |
| Minimum of numbers | min(1, 2) |
| Maximum of numbers | max(1, 2) |
| Cast to integer | int('123') |
| Cast to string | str(123) |
| Cast to boolean | bool(1) |
| Range of numbers | range(5, 10) |
- The functionalities discussed have very speci c applications and act like a SHORTCUT or a CHEAT-SHEET in competitive coding. Having these useful tricks up your sleeve might just give someone the COMPETITIVE EDGE that they were looking for!! Java and Python for Competitive Programming Set 2 Article Tags: Competitive Programming Python 7.
- Python for Data Science Cheat Sheets. Python is one of the most widely used programming languages in the data science field.Python has many packages and libraries that are specifically tailored for certain functions, including pandas, NumPy, scikit-learn, Matplotlib, and SciPy.The most appealing quality of Python is that anyone who wants to learn it, even beginners, can do so quickly and easily.
Other syntax
Cheat Sheets For Python
| Return a value | return 123 |
| Indexing | 'test'[0] |
| Slicing | 'test'[1:3] |
| Continue to next loop iteration | continue |
| Exit the loop | break |
| List append | numbers = numbers + [4] |
| List append (with method call) | numbers.append(4) |
| List item extraction | value = numbers[0] |
| List item assignment | numbers[0] = 123 |
Terminology
| syntax | the arrangement of letters and symbols in code |
| program | a series of instructions for the computer |
| print | write text to the screen |
| string | a sequence of letters surrounded by quotes |
| variable | a storage space for values |
| value | examples: a string, an integer, a boolean |
| assignment | using = to put a value into a variable |
| function | a machine you put values into and values come out |
| call (a function) | to run the code of the function |
| argument | the input to a function call |
| parameter | the input to a function definition |
| return value | the value that is sent out of a function |
| conditional | an instruction that's only run if a condition holds |
| loop | a way to repeatedly run instructions |
| list | a type of value that holds other values |
| tuple | like a list, but cannot be changed |
| indexing | extracting one element at a certain position |
| slicing | extracting some elements in a row |
| dictionary | a mapping from keys to values |
Reminders
- Strings and lists are indexed starting at 0, not 1
- Print and return are not the same concept
- The return keyword is only valid inside functions
- Strings must be surrounded by quotes
- You cannot put spaces in variable or function names
- You cannot add strings and integers without casting
- Consistent indentation matters
- Use a colon when writing conditionals, function definitions, and loops
- Descriptive variable names help you understand your code better
Conditionals
Python Programming Cheat Sheet Pdf
Lists
Python Language Cheat Sheet
Defining functions
Loops
Dictionaries
Comparisons
| Equals |
| Not equals | != |
| Less than | < |
| Less than or equal | <= |
| Greater than | > |
Useful methods
| String to lowercase | 'xx'.lower() |
| String to uppercase | 'xx'.upper() |
| Split string by spaces | 'a b c'.split(' ') |
| Remove whitespace around string | ' a string '.strip() |
| Combine strings into one string | ' '.join(['a', 'b']) |
| String starts with | 'xx'.startswith('x') |
| String ends with | 'xx'.endswith('x') |
| List count | [1, 2].count(2) |
| List remove | [1, 2].remove(2) |
| Dictionary keys | {1: 2}.keys() |
| Dictionary values | {1: 2}.values() |
| Dictionary key/value pairs | {1: 2}.items() |
Python Competitive Programming Cheat Sheet Answers
Other neat bonus stuff
| Zip lists | zip([1, 2], ['one', 'two']) |
| Set | my_set = {1, 2, 3} |
| Set intersection | {1, 2} & {2, 3} |
| Set union | {1, 2} | {2, 3} |
| Index of list element | [1, 2, 3].index(2) |
| Sort a list | numbers.sort() |
| Reverse a list | numbers.reverse() |
| Sum of list | sum([1, 2, 3]) |
| Numbering of list elements | for i, item in enumerate(items): |
| Read a file line by line | for line in open('file.txt'): |
| Read file contents | contents = open('file.txt').read() |
| Random number between 1 and 10 | import random; x = random.randint(1, 10) |
| List comprehensions | [x+1 for x in numbers] |
| Check if any condition holds | any([True, False]) |
| Check if all conditions hold | all([True, False]) |
Missing something?
Let us know here.