C++ ] leetCode 2545 - Sort the Students by Their Kth Score

 

 

리트코드 2545 문제

 

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

 

 

std::sort 함수와 이차원벡터에 익숙하다면 바로 풀 수 있는 문제이다. 

 

2차원 벡터를 정렬할 건데 비교함수에는 1차원 벡터 원소를 인자로 받고 1차원 벡터의 k 인덱스 원소를 비교해서 2차원 벡터를 정렬하면 된다.

 

 

class Solution {
public:
    vector<vector<int>> sortTheStudents(vector<vector<int>>& score, int k) {
        sort(score.begin(), score.end(), [&](vector<int> a, vector<int>b) {
            return a[k] > b[k];
        });
        return score;
    }
};