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:
Below is the implementation to convert a given number into a list of digits:
# 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)
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[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:
# 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)
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['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:
# 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)]
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- 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:
# Python program to demonstrate gcd() function import math
a = 8
b = 24
# Print the GCD of a and b print (math.gcd(a, b))
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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:
# 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)
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(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:
# Python program to print # a string given number of times # Given string str = "India"
# Print the string 2 times print ( str * 2 )
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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:
# Python program to print a list with spaces without loop lis = [ 1 , 2 , 3 , 4 ]
# Printing list elements with spaces print ( * lis)
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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:
# 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 ))
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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:
# 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))
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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:
# 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)))
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{4, 5}