Array Packing

You are given an array of up to four non-negative integers, each less than 256.

Your task is to pack these integers into one number M in the following way:

• The first element of the array occupies the first 8 bits of M;
• The second element occupies next 8 bits, and so on.

Return the obtained integer M.

Note: the phrase "first bits of M" refers to the least significant bits of M - the right-most bits of an integer. For further clarification see the following example.

Example

For a = [24, 85, 0], the output should be

array_packing(a) = 21784

An array [24, 85, 0] looks like [00011000, 01010101, 00000000] in binary. After packing these into one number we get 00000000 01010101 00011000 (spaces are placed for convenience), which equals to 21784.

Input/Output

• [input] array.integer a

  Guaranteed constraints:1 ≤ a.length ≤ 4, 0 ≤ a[i] < 256.

Solution

PYTHON

def array_packing(a):
    return int(
        ''.join(
            [
                format(i, 'b').zfill(8)
                for i in reversed(a)
            ]
        ), 2)


print(array_packing([24, 85, 0]))