Python Tips and Tricks for Competitive Programming

Python Programming language makes everything easier and straightforward. Effective use of its built-in libraries can save a lot of time and help with faster submissions while doing Competitive Programming. Below are few such useful tricks that every Pythonist should have at their fingertips:

• Converting a number into a List of digits using map() Function: 

Below is the implementation to convert a given number into a list of digits:

[1, 2, 3, 4, 5, 6]

• Converting a sentence into a List of words using split() Function: Below is the implementation to convert a sentence into a list of words:

['neveropen', 'is', 'the', 'computer', 'science', 'portal', 'for', 'neveropen']

• Take newline-separated integers as a List: Newline-separated input from the console can be taken in the form of a List using List Comprehension. Below is the implementation to take input of newline-separated integers as a list:

• Calculating GCD/HCF of two numbers: Gcd of two numbers can be computed in python using a built-in function gcd() offered by the Python Math Module.

Below is the implementation to demonstrate gcd() function: 

8

• Print permutations of array: All permutations of an array can be efficiently generated using built-in permutations() method from itertools package. This method takes a List as input and returns an object List of Tuples that contains all permutations.

Below is the implementation of the approach:

(1, 2, 3)
(1, 3, 2)
(2, 1, 3)
(2, 3, 1)
(3, 1, 2)
(3, 2, 1)

• Printing a string multiple times without Loop: Below is the implementation to print a string multiple times without loop using string multiplication technique:

IndiaIndia

• To print a list with spaces without loop: A list can be printed without running the loop by using the * operator in Python.

Below is the implementation to print a list with spaces without loop: 

1 2 3 4

• Convert binary string to decimal: A binary string can be converted to its decimal equivalent using built-in int() function.

Below is the implementation of the above approach: 

10

• To print sorted list with spaces: Sorting any sequence is very easy in Python using a built-in method sorted() and using * symbol to print list with spaces. Sorted() sorts any sequence (list, tuple) and always returns a list with the elements in a sorted manner, without modifying the original sequence.

Below is the implementation to print a sorted list with spaces: 

2 3 4 6 7

• To find common elements in two arrays: The common elements in 2 arrays/lists can be done in a much simpler way using sets. The intersection() function in Python gives the common elements in both arrays/lists.

Below is the implementation to demonstrate intersection() function:

{4, 5}