有一个3*3的Mat变量,元素分别是1、2、3、4、5、6、7、8、9，现把这个矩阵展开，顺序是1、2、3、6、5、4、7、8、9，用c++和opencv写出代码

以下是用C++和OpenCV实现将3*3的Mat变量展开的代码：

#include <iostream>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main()
{
    Mat mat(3, 3, CV_8UC1);
    mat.at<uchar>(0, 0) = 1;
    mat.at<uchar>(0, 1) = 2;
    mat.at<uchar>(0, 2) = 3;
    mat.at<uchar>(1, 0) = 4;
    mat.at<uchar>(1, 1) = 5;
    mat.at<uchar>(1, 2) = 6;
    mat.at<uchar>(2, 0) = 7;
    mat.at<uchar>(2, 1) = 8;
    mat.at<uchar>(2, 2) = 9;

    Mat result(1, 9, CV_8UC1);
    int index = 0;
    for (int i = 0; i < mat.rows; i++) {
        if (i % 2 == 0) {
            for (int j = 0; j < mat.cols; j++) {
                result.at<uchar>(0, index) = mat.at<uchar>(i, j);
                index++;
            }
        }
        else {
            for (int j = mat.cols - 1; j >= 0; j--) {
                result.at<uchar>(0, index) = mat.at<uchar>(i, j);
                index++;
            }
        }
    }

    cout << "展开后的矩阵为：" << endl;
    for (int i = 0; i < result.cols; i++) {
        cout << (int)result.at<uchar>(0, i) << " ";
    }
    cout << endl;

    return 0;
}

输出结果为：

展开后的矩阵为：
1 2 3 6 5 4 7 8 9