# [3239\. Minimum Number of Flips to Make Binary Grid Palindromic I](https://leetcode.com/problems/minimum-number-of-flips-to-make-binary-grid-palindromic-i/)

:::spoiler Hint

:::

:::spoiler Solution

class Solution {
public:
    int minFlips(vector<vector<int>>& grid)
    {
        int m = grid.size(), n = grid[0].size();
        int row = 0, col = 0;
        for (int i = 0; i < m; ++i)
        {
            int left = 0, right = n - 1;
            while (left < right)
            {
                if (grid[i][left] != grid[i][right]) ++row;
                ++left; --right;
            }
        }

        for (int j = 0; j < n; ++j)
        {
            int up = 0, down = m - 1;
            while (up < down)
            {
                if (grid[up][j] != grid[down][j]) ++col;
                ++up; --down;
            }
        }        
        return min(row, col);
    }
};

- T: $O(m \cdot n)$
- S: $O(1)$
:::