Introduction

In this blog post, we will explore how to solve the LeetCode problem "2545" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

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. Example 1: Input: score = [[10,6,9,1],[7,5,11,2],[4,8,3,15]], k = 2 Output: [[7,5,11,2],[10,6,9,1],[4,8,3,15]] Explanation: In the above diagram, S denotes the student, while E denotes the exam. - The student with index 1 scored 11 in exam 2, which is the highest score, so they got first place. - The student with index 0 scored 9 in exam 2, which is the second highest score, so they got second place. - The student with index 2 scored 3 in exam 2, which is the lowest score, so they got third place. Example 2: Input: score = [[3,4],[5,6]], k = 0 Output: [[5,6],[3,4]] Explanation: In the above diagram, S denotes the student, while E denotes the exam. - The student with index 1 scored 5 in exam 0, which is the highest score, so they got first place. - The student with index 0 scored 3 in exam 0, which is the lowest score, so they got second place. Constraints: m == score.length n == score[i].length 1 <= m, n <= 250 1 <= score[i][j] <= 105 score consists of distinct integers. 0 <= k < n

Explanation

Here's a breakdown of the solution:

• Sort based on the kth exam: Use a custom sorting function (lambda) to sort the rows (students) of the matrix based on their score in the kth exam. The sorting will be in descending order (highest score first).

• Leverage Python's built-in sort: Utilize Python's sort or sorted method, which is highly optimized for sorting. We'll use the sorted function to maintain the original matrix and return a new sorted matrix.

• Runtime & Storage Complexity: O(m log m) time complexity due to the sorting operation, where m is the number of students (rows). O(m * n) storage complexity for storing the sorted matrix, where n is the number of exams.

Code

    def sortTheStudents(score: list[list[int]], k: int) -> list[list[int]]:
    """
    Sorts the students based on their scores in the kth exam.

    Args:
        score: A matrix representing student scores.
        k: The index of the exam to sort by.

    Returns:
        The sorted matrix.
    """
    return sorted(score, key=lambda row: row[k], reverse=True)