Binary Representation
The Question
Given a (decimal - e.g. 3.72) number that is passed in as a string, return the binary representation that is passed in as a string. If the fractional part of the number can not be represented accurately in binary with at most 32 characters, return ERROR.
Example
For n = "3.72", return "ERROR".
For n = "3.5", return "11.1".The Caveate
The problem itself is not difficult, but there are many corner cases to consider, such as 0.1, 1.0, 1 , etc., as well as the case where the fractal part cannot be represented by 32 bit integer.
The Solution
class Solution:
#@param n: Given a decimal number that is passed in as a string
#@return: A string
def binaryRepresentation(self, n):
# write you code here
# create two strings that are used as cache
b_intg = ""
b_frac = ""
# if there's no decimal point, we can't split the string with dot.
if '.' in n:
[intg, frac] = n.split('.')
intg, frac = int(intg), float("0."+frac)
else:
intg = int(n)
# construct the integer part
temp = intg
while temp > 0:
b_intg = str(temp%2) + b_intg
temp = temp / 2
# construct the fractal part
temp = frac
count = 0
while frac > 0:
count += 1
if count >= 32:
return "ERROR"
frac = frac * 2
b_frac = b_frac + str(frac)[0]
if frac >= 1:
frac = frac - 1
# if b_intg is empty, we know that intg is zero, so we need to specify
# that by pushing a leading zero here.
if b_intg == "":
b_intg = "0"
# if b_frac is empty, we simply return the integer part, no decimal point.
if b_frac == "":
return b_intg
# if both are non-empty, then we join the two parts with a decimal point.
return '.'.join([b_intg, b_frac])