Python Introducton to Sets HackerRank 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.
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.
the 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 or 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, 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
Solution:
def average(array):
my_set = set(array)
avg = sum(my_set)/len(my_set)
return (avg)
if __name__ == '__main__':
n = int(input())
arr = list(map(int, input().split()))
result = average(arr)
print(result)
Steps Used in solving the problem -
Step 1: First we created a function average which will take an array as input.
Step 2: In the second step we converted our array into a set so that similar elements get eliminated.
Step 3: then we divided the sum of all distinct heights by the total number of distinct heights to find the average.
Step 4: At last we returned our average.
