# 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

This operation also removes element x from the set.
If element x does not exist, it does not raise a KeyError.

Example:

>>> s = set([1, 2, 3, 4, 5, 6, 7, 8, 9])
>>> print s
set([1, 2, 3, 4, 6, 7, 8, 9])
None
>>> print s
set([1, 2, 3, 6, 7, 8, 9])
>>> 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()
>>> print s.pop()
1
>>> print s
set([])
>>> print s.pop()
KeyError: pop from an empty set

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 :

```                            ```Solution in C :

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

## Kundu and Tree

Kundu is true tree lover. Tree is a connected graph having N vertices and N-1 edges. Today when he got a tree, he colored each edge with one of either red(r) or black(b) color. He is interested in knowing how many triplets(a,b,c) of vertices are there , such that, there is atleast one edge having red color on all the three paths i.e. from vertex a to b, vertex b to c and vertex c to a . Note that

## Super Maximum Cost Queries

Victoria has a tree, T , consisting of N nodes numbered from 1 to N. Each edge from node Ui to Vi in tree T has an integer weight, Wi. Let's define the cost, C, of a path from some node X to some other node Y as the maximum weight ( W ) for any edge in the unique path from node X to Y node . Victoria wants your help processing Q queries on tree T, where each query contains 2 integers, L and

## Contacts

We're going to make our own Contacts application! The application must perform two types of operations: 1 . add name, where name is a string denoting a contact name. This must store name as a new contact in the application. find partial, where partial is a string denoting a partial name to search the application for. It must count the number of contacts starting partial with and print the co

## No Prefix Set

There is a given list of strings where each string contains only lowercase letters from a - j, inclusive. The set of strings is said to be a GOOD SET if no string is a prefix of another string. In this case, print GOOD SET. Otherwise, print BAD SET on the first line followed by the string being checked. Note If two strings are identical, they are prefixes of each other. Function Descriptio

## Cube Summation

You are given a 3-D Matrix in which each block contains 0 initially. The first block is defined by the coordinate (1,1,1) and the last block is defined by the coordinate (N,N,N). There are two types of queries. UPDATE x y z W updates the value of block (x,y,z) to W. QUERY x1 y1 z1 x2 y2 z2 calculates the sum of the value of blocks whose x coordinate is between x1 and x2 (inclusive), y coor

## Direct Connections

Enter-View ( EV ) is a linear, street-like country. By linear, we mean all the cities of the country are placed on a single straight line - the x -axis. Thus every city's position can be defined by a single coordinate, xi, the distance from the left borderline of the country. You can treat all cities as single points. Unfortunately, the dictator of telecommunication of EV (Mr. S. Treat Jr.) do