HackerRank Python Solution - Sets - .discard(), .remove() & .pop()

.remove(x):

• This operation removes element x from the set.

• If element x does not exist, it raises a KeyError.

• The .remove(x) operation returns None.

Example:

>>> s = set([1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> s.remove(5)
>>> print s
set([1, 2, 3, 4, 6, 7, 8, 9])
>>> print s.remove(4)
None
>>> print s
set([1, 2, 3, 6, 7, 8, 9])
>>> s.remove(0)
KeyError: 0

.discard(x):

• This operation also removes element x from the set.

• If element x does not exist, it does not raise a KeyError.

• The .discard(x) operation returns None.

Example:

>>> s = set([1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> s.discard(5)
>>> print s
set([1, 2, 3, 4, 6, 7, 8, 9])
>>> print s.discard(4)
None
>>> print s
set([1, 2, 3, 6, 7, 8, 9])
>>> s.discard(0)
>>> print s
set([1, 2, 3, 6, 7, 8, 9])

.pop():

• This operation removes and returns an arbitrary element from the set.

• If there are no elements to remove, it raises a KeyError.

Example:

>>> s = set([1])
>>> print s.pop()
1
>>> print s
set([])
>>> print s.pop()
KeyError: pop from an empty set

Task:

• You have a non-empty set s, and you have to execute N commands given in N lines.

• The commands will be pop, remove and discard.

Input Format:

• The first line contains integer n, the number of elements in the set s.

• The second line contains n space-separated elements of set s. All of the elements are non-negative integers, less than or equal to 9.

• The third line contains integer N, the number of commands.

• The next N lines contain either pop, remove and/or discard commands followed by their associated value.

Constraints:

• 0 < n < 20
• 0 < N < 20

Output Format:

• Print the sum of the elements of set s on a single line.

Sample Input:

9
1 2 3 4 5 6 7 8 9
10
pop
remove 9
discard 9
discard 8
remove 7
pop 
discard 6
remove 5
pop 
discard 5

Sample Output:

4

Explanation:

• After completing these 10 operations on the set, we get set([4]). Hence, the sum is 4.

• Note: Convert the elements of set s to integers while you are assigning them. To ensure the proper input of the set, we have added the first two lines of code to the editor.

Solution:

n = int(input())
s = set(map(int,input().split()))

for _ in range(int(input())):
    opr =input().split()
    
    if len(opr) < 2:
        s.pop()
    else:
        if opr[1] == 'remove':
            s.remove(int(opr[1]))
        else:
            s.discard(int(opr[1]))
        
print(sum(s))

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