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# 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:

## Python3

 `# Python program to convert a``# number to a list of digits` `# Given number``n ``=` `123456` `# Stores the list of digits``lis ``=` `list``(``map``(``int``, ``str``(n)))` `# Print the digits``print``(lis)`

Output:

`[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:

## Python3

 `# Python program to convert``# a sentence to a list of words` `# Given sentence``sentence ``=` `"GeeksforGeeks is the computer science portal for geeks"` `# Convert the sentence``# into a list of words``lis ``=` `list``(sentence.split())` `# Print the list of words``print``(lis)`

Output:

`['GeeksforGeeks', 'is', 'the', 'computer', 'science', 'portal', 'for', 'geeks']`

• 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:

## Python3

 `# Python program to take``# newline-separated input``# in the form of a list` `# Given input``n ``=` `int``(``input``())` `lis ``=` `[``int``(``input``()) ``for` `_ ``in` `range``(n)]`

Below is the implementation to demonstrate gcd() function:

## Python3

 `# Python program to demonstrate gcd() function``import` `math``a ``=` `8``b ``=` `24` `# Print the GCD of a and b``print``(math.gcd(a, b))`

Output:

`8`

Below is the implementation of the approach:

## Python3

 `# Python program to print all``# permutations using library function``from` `itertools ``import` `permutations` `# Get all permutations of [1, 2, 3]``perm ``=` `permutations([``1``, ``2``, ``3``])` `# Print the obtained permutations``for` `i ``in` `list``(perm):``    ``print` `(i)`

Output:

```(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:

## Python3

 `# Python program to print``# a string given number of times` `# Given string``str` `=``"India"` `# Print the string 2 times``print``(``str` `*` `2``)`

Output:

`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:

## Python3

 `# Python program to print a list with spaces without loop``lis ``=` `[``1``, ``2``, ``3``, ``4``]` `# Printing list elements with spaces``print``(``*``lis)`

Output:

`1 2 3 4`

Below is the implementation of the above approach:

## Python3

 `# Python program to convert a``# binary string to its decimal``# equivalent using int() function` `# Given string``binary ``=` `"1010"` `# Print decimal equivalent``print``(``int``(binary, ``2``))`

Output

`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:

## Python3

 `# Python program to print a sorted list with``# spaces using sorted() function``lis ``=` `[``6``, ``2``, ``7``, ``3``, ``4``]` `# Print the sorted sequence``print``(``*``sorted``(lis))`

Output:

`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:

## Python3

 `# Python program to print common elements in``# both the list using intersection() function``array1 ``=` `[``4``, ``5``, ``6``, ``7``, ``8``]``array2 ``=` `[``3``, ``4``, ``5``, ``1``, ``72``]` `# Print the common elements``print``(``set``(array1).intersection(``set``(array2)))`

Output

`{4, 5}`

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