binary_twos_complement.py

# Information on 2's complement: https://en.wikipedia.org/wiki/Two%27s_complement


deftwos_complement(number: int) ->str:
"""
 Take in a negative integer 'number'.
 Return the two's complement representation of 'number'.

 >>> twos_complement(0)
 '0b0'
 >>> twos_complement(-1)
 '0b11'
 >>> twos_complement(-5)
 '0b1011'
 >>> twos_complement(-17)
 '0b101111'
 >>> twos_complement(-207)
 '0b100110001'
 >>> twos_complement(1)
 Traceback (most recent call last):
 ...
 ValueError: input must be a negative integer
 """
ifnumber>0:
raiseValueError("input must be a negative integer")
binary_number_length=len(bin(number)[3:])
twos_complement_number=bin(abs(number) - (1<<binary_number_length))[3:]
twos_complement_number= (
 (
"1"
+"0"* (binary_number_length-len(twos_complement_number))
+twos_complement_number
 )
ifnumber<0
else"0"
 )
return"0b"+twos_complement_number


if__name__=="__main__":
importdoctest

doctest.testmod()