HackerRank Python: Finding the percentage Solution

Table of Contents

Question

The provided code stub will read in a dictionary containing key/value pairs of name:[marks] for a list of students. Print the average of the marks array for the student name provided, showing 2 places after the decimal.

Example

marks key: value pairs are
‘alpha’:[20, 30, 40]
‘beta’:[30, 50, 70]
query_name = ‘beta’

The query_name is ‘beta’. beta’s average score is (30 + 50 + 70)/3 = 50.0.

The query_name is ‘beta’. beta’s average score is .

Input Format

The first line contains the integer , the number of students’ records. The next lines contain the names and marks obtained by a student, each value separated by a space. The final line contains query_name, the name of a student to query.

Constraints

2 ≤ n ≤ 10
0 ≤ marks[i] ≤ 100
length of the marks array = 3

Output Format

Print one line: The average of the marks obtained by the particular student correct to 2 decimal places.

Sample Input 0

3
Krishna 67 68 69
Arjun 70 98 63
Malika 52 56 60
Malika

Sample Output 0

56.00

Explanation 0

Marks of Malika are {52, 56, 60} whose average is (52 +56 +60)/3 ⇒ 56

Sample Input 1

2
Harsh 25 26.5 28
Anurag 26 28 30
Harsh

Sample Output 1

26.50

Solution

				
					n = int(input())
student_marks = {}

for _ in range(n):
    name, *marks = input().split()
    marks = list(map(float, marks))
    student_marks[name] = marks

query_name = input()

if query_name in student_marks:
    marks = student_marks[query_name]
    average = sum(marks) / len(marks)
    print("{:.2f}".format(average))

Explanation

Read the number of student records (n) from input.
Initialize an empty dictionary student_marks to store the marks of each student.
Iterate n times and read the name and marks of each student from input. Split the input line by spaces, and convert the marks to a list of floats.
Store the marks as a value in the student_marks dictionary, with the name as the key.
Read the query_name from input.
If the query_name exists in the student_marks dictionary, retrieve the marks list for that name.
Calculate the average by summing the marks and dividing by the length of the marks list.
Print the average with 2 decimal places using the format specifier "{:.2f}".