Set.union() | HackerRank Solutions

 In this problem we have two  new paper subscription english and french and two  group of set students who  subscribed one and another newspaper  and some of subscribe both so  our task to  find those who subscribed both and return there length total , below you  can see what task stated and how to  write  we achieve this using set()  union function which provide use this facility  its can we done byt both

| operator

 or 

 s1.uniont(s2)

The first line contains an integer, , the number of students who have subscribed to the English newspaper.
The second line contains  space separated roll numbers of those students.
The third line contains , the number of students who have subscribed to the French newspaper.
The fourth line contains  space separated roll numbers of those students.

Problem:https://www.hackerrank.com/challenges/py-set-union/problem?isFullScreen=true

Code:

# Enter your code here. Read input from STDIN. Print output to STDOUT

n = int(input())

#s1 = set(map(int, input().split()))

s1 = set(map(int, input().split()[:n]))

b = int(input())

#s2 = set(map(int, input().split()))

s2 = set(map(int, input().split()[:b]))

print(len(s1|s2)) #union or print(len(s1.union(s2)))

'''

In this code, we first read the size of the two sets (n and b) from the input.

We then read the elements for each set, convert them to integers,

and form sets (s1 and s2). The use of the slice [:n] and [:b] ensures that

even if more elements are provided in the input, only the first n or b elements

are considered. This helps to control the size of the sets,

as the number of elements in each set is exactly what was specified by the user.

If fewer elements are provided than the specified size,

it simply uses what is available. Finally,

we calculate and print the size of the union of the two sets.

The union of two sets combines all unique elements from both sets,

ensuring there are no duplicates. The len() function then counts the

number of unique elements in the union and prints the result.

'''

1. n = int(input())

• This line reads the first integer input, which indicates the size of the first set (s1).

• int(input()) converts the input string to an integer.

2. s1 = set(map(int, input().split()[:n]))

• This line constructs the first set s1.

• input() reads a line of input (a string).

• .split() splits the string into a list of individual elements based on spaces.

• map(int, ...) converts each element in the list to an integer.

• [:n] takes only the first n elements from the split input, ensuring that the size of the set matches the integer n read earlier.

• set(...) converts the list of integers into a set (automatically removing duplicates).

• So, this line reads n integers, creates a set out of them, and stores it in s1.

3. b = int(input())

• Similar to n, this reads the second integer input, which represents the size of the second set (s2).

4. s2 = set(map(int, input().split()[:b]))

• This line creates the second set s2 in the same way as s1:

  • Reads the input, splits it, maps the values to integers, takes the first b elements, and converts them into a set.

5. print(len(s1|s2))

or print(len(s1.union(s2)))

• This line calculates the union of the two sets and prints the number of elements in the union.

• s1|s2 is the set union operator in Python, which returns a new set containing all unique elements from both s1 and s2.

• .union(s2) is an alternative method to perform the union between s1 and s2. Both methods are equivalent in this case.

• len(...) calculates the number of elements in the union set, which is then printed.

Why Each Piece is Needed:

• Input and Size Control (n, b): The input sizes (n and b) help control the number of elements that are read for each set. This is useful for validation or ensuring that only the necessary number of elements are processed.

• Set Operations: Using sets makes it easy to handle unique elements, because sets automatically discard duplicates. This is critical when calculating unions to ensure you don’t count repeated elements.

• Union: The union operation (s1|s2) combines both sets and removes duplicates, which is exactly what is needed to calculate the number of distinct elements across both sets.

Output:

The final output prints the number of distinct elements that exist in either of the two sets s1 or s2. It does so by performing a union operation and then measuring the size of the resulting set.