Medium - Sum in a Matrix

https://leetcode.com/problems/sum-in-a-matrix/description/

Sum in a Matrix - LeetCode

문제 설명

You are given a 0-indexed 2D integer array nums. Initially, your score is 0. Perform the following operations until the matrix becomes empty:

1. From each row in the matrix, select the largest number and remove it. In the case of a tie, it does not matter which number is chosen.
2. Identify the highest number amongst all those removed in step 1. Add that number to your score.

Return the final score.

Constraints:

• 1 <= nums.length <= 300
• 1 <= nums[i].length <= 500
• 0 <= nums[i][j] <= 10 ** 3

 

예시

Input: nums = [[7,2,1],[6,4,2],[6,5,3],[3,2,1]]
Output: 15
Explanation: In the first operation, we remove 7, 6, 6, and 3. We then add 7 to our score. Next, we remove 2, 4, 5, and 2. We add 5 to our score. Lastly, we remove 1, 2, 3, and 1. We add 3 to our score. Thus, our final score is 7 + 5 + 3 = 15.

Input: nums = [[1]]
Output: 1
Explanation: We remove 1 and add it to the answer. We return 1.

풀이

class Solution:
    def matrixSum(self, nums: List[List[int]]) -> int:
        num_col = len(nums[0])
        max_per_row = [0, ] * num_col

        for row in range(len(nums)):
            cur = sorted(nums[row], reverse=True)
            for i in range(num_col):
                max_per_row[i] = max(cur[i], max_per_row[i])

        return sum(max_per_row)

 

 

 

문제에서 요구하는 operation만 적용한 풀이. 왜 Medium인지는 의문...