1380. Lucky Numbers in a Matrix

class Solution {
public:
    vector<int> luckyNumbers (vector<vector<int>>& matrix)
    {
        int m = matrix.size(), n = matrix[0].size();

        int rMinMax = INT_MIN;
        for (int i = 0; i < m; ++i)
        {

            int rMin = INT_MAX;
            for (int j = 0; j < n; ++j)
            {
                rMin = min(rMin, matrix[i][j]);
            }
            rMinMax = max(rMinMax, rMin);
        }

        int cMaxMin = INT_MAX;
        for (int i = 0; i < n; ++i)
        {

            int cMax = INT_MIN;
            for (int j = 0; j < m; j++)
            {
                cMax = max(cMax, matrix[j][i]);
            }
            cMaxMin = min(cMaxMin, cMax);
        }
        if (rMinMax == cMaxMin)
        {
            return {rMinMax};
        }
        return {};
    }
};

• T: $O(M \cdot N)$
• S: $O(1)$