Given an m x n matrix of distinct numbers, return all lucky numbers in the matrix in any order.
A lucky number is an element of the matrix such that it is the minimum element in its row and maximum in its column.
Example 1:
Input: matrix = [[3,7,8],[9,11,13],[15,16,17]]
Output: [15]
Explanation: 15 is the only lucky number since it is the minimum in its row and the maximum in its column.
Example 2:
Input: matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]]
Output: [12]
Explanation: 12 is the only lucky number since it is the minimum in its row and the maximum in its column.
Example 3:
Input: matrix = [[7,8],[1,2]]
Output: [7]
Explanation: 7 is the only lucky number since it is the minimum in its row and the maximum in its column.
Solution
class Solution:
def luckyNumbers (self, matrix: List[List[int]]) -> List[int]:
row_mins = set()
col_maxs = set()
for row in matrix:
row_mins.add(min(row))
for col in zip(*matrix):
col_maxs.add(max(col))
return list(row_mins.intersection(col_maxs))