Set.discard(), remove() & pop() Python


Problem Statement :


.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 return 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 contains either pop, remove and/or discard commands followed by their associated value.


Constraints:
     1.   0<n<20
     2.   0<N<20


Output Format:

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


Solution :



title-img 


                            Solution in C :

n = input()
s = set(map(int, input().split()))
for i in range(int(input())):
    c = input().split()
    if c[0] == 'pop':
        s.pop()
    elif c == 'remove':
        s.remove(int(c[1]))
    else:
        s.discard(int(c[1]))
print(sum(s))








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