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public void (int[][] matrix) {
    if (matrix == null || matrix.length == 0 || matrix[0] == null || matrix[0].length == 0)
        return;
    int n = matrix.length - 1;
    
    for (int i = 0; i < matrix.length / 2 ; ++i) {
        for (int j = 0; j < matrix[0].length; ++j) {
            int temp = matrix[i][j];
            matrix[i][j] = matrix[n - i][j];
            matrix[n - i][j] = temp;
        }
    }
    // symmetry swap
    for (int i = 0; i < matrix.length; ++i) {
        for (int j = i + 1; j < matrix[0].length; ++j) {
            int temp = matrix[i][j];
            matrix[i][j] = matrix[j][i];
            matrix[j][i] = temp;
        }
    }
}