Introduction to Sets in Python - HackerRank Solution

Problem

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.


Task

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 Heights


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].


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

Average = 1355 / 8 = 169.375


Solution

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
def average(array):
    array = set(array)
    n = len(array)
    sums = sum(array)
    
    result = sums/n
    return result
        

if __name__ == '__main__':
    n = int(input())
    arr = list(map(int, input().split()))
    result = average(arr)
    print(result)
Next Post Previous Post
No Comment
Add Comment
comment url