Sort students by marks in Java

The arrays roll[] and marks[] store student roll numbers and their corresponding marks. The objective is to reorder the roll numbers such that they follow the descending order of marks, while maintaining the correct roll-marks association.

Example:

Input: roll[] = {101, 108, 103, 105}, marks[] = {70, 80, 40, 90}
Output: {105, 108, 101, 103}
Explanation: After sorting marks[] in decreasing order as {90, 80, 70, 40}, the corresponding roll[] values are rearranged to {105, 108, 101, 103} respectively.

Approach

Follow these steps to solve the problem efficiently:

• Create a custom Student class to store marks and the corresponding roll number together
• Traverse both arrays and store each marks–roll pair as a Student object in an ArrayList
• Sort the list using Collections.sort() based on marks in decreasing order
• Traverse the sorted list and print the roll numbers in the new order based on marks

105 108 101 103 

• Time Complexity: O(N log N), where N is the number of students.
• Space Complexity: O(N) due to the ArrayList storing the student objects.