## Algorithm

Problem Name: Python - Introduction to Sets

In this HackerRank Functions in PYTHON problem solution,

A set is an unordered collection of elements without duplicate entries.
When printed, iterated or converted into a sequence, its elements will appear in an arbitrary order.

Example

``````>>> print set()
set([])

>>> print set('HackerRank')
set(['a', 'c', 'e', 'H', 'k', 'n', 'r', 'R'])

>>> print set([1,2,1,2,3,4,5,6,0,9,12,22,3])
set([0, 1, 2, 3, 4, 5, 6, 9, 12, 22])

>>> print set((1,2,3,4,5,5))
set([1, 2, 3, 4, 5])

>>> print set(set(['H','a','c','k','e','r','r','a','n','k']))
set(['a', 'c', 'r', 'e', 'H', 'k', 'n'])

>>> print set({'Hacker' : 'DOSHI', 'Rank' : 616 })
set(['Hacker', 'Rank'])

>>> print set(enumerate(['H','a','c','k','e','r','r','a','n','k']))
set([(6, 'r'), (7, 'a'), (3, 'k'), (4, 'e'), (5, 'r'), (9, 'k'), (2, 'c'), (0, 'H'), (1, 'a'), (8, 'n')])
``````

Basically, sets are used for membership testing and eliminating duplicate entries.

Now, let's use our knowledge of sets and help Mickey.

Ms. Gabriel Williams is a botany professor at District College. One day, she asked her student Mickey to compute the average of all the plants with distinct heights in her greenhouse.

Formula used:

Average = Sum of Distinct Heights / Total Number of Distinct Height

Function Description

Complete the average function in the editor below.

average has the following parameters:

• int arr: an array of integers

Returns

• float: the resulting float value rounded to 3 places after the decimal

Input Format

The first line contains the integer, N , the size of arr.

The second line contains the N space-separated integers, arr[i]

Constraints

0 < N <= 100

Sample Input

```STDIN                                       Function
-----                                       --------
10                                          arr[] size N = 10
161 182 161 154 176 170 167 171 170 174     arr = [161, 181, ..., 174]
```

Sample Output

``````169.375
``````

Explanation

Here, set ([154,161,167,170,171,171,174,176,182]) is the set containing the distinct heights. Using the sum() and len() functions, we can compute the average.

Average = 1355/ 8 = 169.375

## Code Examples

### #1 Code Example with Python Programming

```Code - Python Programming```

``````
def average(array):
"""
Function to return distinct average from an array.
"""
dist_ele = set(array)
dist_len = len(dist_ele)
result = sum(dist_ele)/ dist_len
return ("%.3f" % result)
``````
Copy The Code &