leetcode-1380. Lucky number in matrix

To give you one m * n Matrix , The number in the matrix Each are not identical . Please press arbitrarily Return all the lucky numbers in the matrix in order .

Lucky number refers to the elements in the matrix that meet the following two conditions at the same time ：

The smallest of all elements in the same row
The largest of all elements in the same column

Example 1：

Input ：matrix = [[3,7,8],[9,11,13],[15,16,17]]
Output ：[15]
explain ：15 Is the only lucky number , Because it is the smallest value in its row , It is also the maximum value in the column .
Example 2：

Input ：matrix = [[1,10,4,2],[9,3,8,7],[15,16,17,12]]
Output ：[12]
explain ：12 Is the only lucky number , Because it is the smallest value in its row , It is also the maximum value in the column .
Example 3：

Input ：matrix = [[7,8],[1,2]]
Output ：[7]

Tips ：

m == mat.length
n == mat[i].length
1 <= n, m <= 50
1 <= matrix[i][j] <= 10^5
All elements in the matrix are different

class Solution {
    
    public List<Integer> luckyNumbers (int[][] matrix) {
    
        int m=matrix.length,n=matrix[0].length;
        Set<Integer> minSet=new HashSet<>();
        List<Integer> res=new ArrayList<>();
        for(int i=0;i<m;i++){
    
            int min=Integer.MAX_VALUE;
            for(int j=0;j<n;j++){
    
                min=Math.min(min,matrix[i][j]);
            }
            minSet.add(min);
        }
        for(int j=0;j<n;j++){
    
            int max=Integer.MIN_VALUE;
            for(int i=0;i<m;i++){
    
                max=Math.max(max,matrix[i][j]);
            }
            if(minSet.contains(max)){
    
                res.add(max);
            }
        }
        return res;
    }
}