Sort the Students by Their Kth Score

Problem Description

There is a class with m students and n exams. You are given a 0-indexed m x n integer matrix score, where each row represents one student and score[i][j] denotes the score the ith student got in the jth exam. The matrix score contains distinct integers only. You are also given an integer k. Sort the students (i.e., the rows of the matrix) by their scores in the kth (0-indexed) exam from the highest to the lowest. Return the matrix after sorting it.

Key Insights

• Each row in the matrix represents a different student, and each column represents a different exam.
• We need to sort the students based on a specific exam score, which is given by the index k.
• Since the scores are distinct, there is a clear ordering for sorting.

Space and Time Complexity

Time Complexity: O(m log m) - where m is the number of students (rows in the matrix). This is due to the sorting operation. Space Complexity: O(m) - for storing the sorted results.

Solution

To solve this problem, we will use the following approach:

1. Utilize a sorting algorithm that allows us to sort the rows of the matrix based on the scores in the kth exam.
2. We can achieve this by using a custom sorting function that extracts the kth score from each row and sorts the rows in descending order based on these values.
3. The built-in sort function in most programming languages allows us to specify a key for sorting, which we will use to reference the appropriate column (k).

Code Solutions