func flipInvertImage(_ array: [[Int]]) -> [[Int]] {
    var array2d = array

    //flip
    for i in 0..<array.count {
        let subarray = array2d[i] //[[1,2,3,4], [5,6,7,8], [9,10,11,12]] here each(3) column has 4 rows

        for j in 0..<subarray.count {
            array2d[i][j] = array2d[i][j] == 0 ? 1 : 0
        }
    }

    //invert
    for i in 0..<array.count {
        let flippedArr = array2d[i]
        for j in 0..<flippedArr.count {
            let k = flippedArr[flippedArr.count-j-1]
            array2d[i][j] = k
        }
    }

    return array2d
}