illegal_arrays.py

#!/usr/bin/env python3

from sys import argv

"""
Converts a string representation of a sorted array of integers `s` into a bitfield.

e.g. indicesToBin("1 2 4 9 10 13 15 17 18 20 21 25 26 28 29 33 34 36 37 38 39")
     -> "01101000011001010110110001101100011011110"

@return a string representation of the resulting bitfield.
"""
def indicesToBin(s):
    L = [int(ch) for ch in s.split(' ')]
    size = L[-1] + (8 - (L[-1] % 8))
    bitfield = [0 for i in range(size + 1)]

    for n in L:
        bitfield[n] = 1

    return ''.join(str(b) for b in bitfield)

"""
Converts string `s` into a sorted array of integers where each value n corresponds to the n-th
index in a bitfield comprising the binary formatted string in which the bit is turned on.

e.g. strToArrayIndices("hello")
     -> "1 2 4 9 10 13 15 17 18 20 21 25 26 28 29 33 34 36 37 38 39"

@return a string representation of the resulting array.
"""
def strToArrayIndices(s):
    L = [i for (i, bit) in enumerate(''.join([format(ord(ch), '08b') for ch in s])) if bit == '1']
    return ' '.join(str(x) for x in L)

def main(cmd, s):
    if cmd == 'to':
        print(strToArrayIndices(s))
    elif cmd == 'from':
        print(indicesToBin(s))

if __name__ == '__main__':
    if len(argv) != 3:
        print("Usage: ./translate [to|from] [string]")
        exit(1)

    cmd = argv[1].lower()
    s = argv[2]

    if cmd not in ["to", "from"]:
        print("Usage: ./translate [to|from] [string]")
        exit(1)

    main(cmd, s)