HackerRank Nested Lists Python solution
Given the names and grades for each student in a Physics class of N students, store them in a nested list and print the name(s) of any student(s) having the second lowest grade.
Note: If there are multiple students with the same grade, order their names alphabetically and print each name on a new line.
Input Format
The first line contains an integer, N , the number of students.
The 2N subsequent lines describe each student over 2 lines; the first line contains a student's name, and the second line contains their grade.
Constraints
- There will always be one or more students having the second lowest grade.
Output Format
Print the name(s) of any student(s) having the second lowest grade in Physics; if there are multiple students, order their names alphabetically and print each one on a new line.
Sample Input 0
5
Harry
37.21
Berry
37.21
Tina
37.2
Akriti
41
Harsh
39
Sample Output 0
Berry
Harry
Explanation 0
There are 5 students in this class whose names and grades are assembled to build the following list:
python students = [['Harry', 37.21], ['Berry', 37.21], ['Tina', 37.2], ['Akriti', 41], ['Harsh', 39]]
The lowest grade of 37.2 belongs to Tina. The second lowest grade of 37.21 belongs to both Harry and Berry, so we order their names alphabetically and print each name on a new line.
Solution in Python3
Beginner friendly solution with comments
#take value of n
no_of_students = int(input())
#create empty list
records = []
#append record of each student name,score in a for loop
for i in range(no_of_students):
name = input()
score = float(input())
records.append([name, score])
#convert list of records to a python dictionary
# [['Harry', 37.21], ['Berry', 37.21]] becomes
# {'Harry': 37.21, 'Berry': 37.21}
records = dict(records)
#get only values from our dictionary and use set function to rmeove duplicate score then sort it in ascending order
scores = sorted(set(records.values()))
#index 1 has the 2nd lowest score
second_lowest_score = scores[1]
#create a list of names of students who has 2nd lowest score using list comprehension
second_lowest_students = [name for name,score in records if score==second_lowest_score]
#sort names in alphabetical order
second_lowest_students.sort()
#loop through each name and print
for name in second_lowest_students:
print(name)
Beginner friendly solution without comments
no_of_students = int(input())
records = []
for i in range(no_of_students):
name = input()
score = float(input())
records.append([name, score])
records = dict(records)
scores = sorted(set(records.values()))
second_lowest_score = scores[1]
second_lowest_students = [name for name,score in records if score==second_lowest_score]
second_lowest_students.sort()
for name in second_lowest_students:
print(name)
Advanced users
students = [[input(),float(input())] for i in range(int(input()))]
second_highest = sorted(set(j for i,j in students))[1]
print("\n".join(sorted(i for i,j in students if j==second_highest)))