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September 12, 2017 21:27
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Convert repeating decimals to fractions.
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import sys | |
def err(section): | |
print("ERROR [{section}]: Bad input (not a number)".format(section=section)) | |
sys.exit(1) | |
def stoi(s): | |
return int("".join(("0" + s))) | |
def int_repeat(n, k): | |
x = 1 | |
for _ in range(k - 1): | |
x = x * 10 + 1 | |
return n * x | |
def gcd(x, y): | |
a = max(x, y) | |
b = min(x, y) | |
while b > 0: | |
temp = a % b | |
a = b | |
b = temp | |
return a | |
while True: | |
inp = input().lower() | |
if inp[0:4] == "exit": | |
sys.exit(0) | |
inp.replace(",", ".") | |
# Substract 1, 2 because chars '(' and '.' will be removed from string | |
dot = inp.find(".") - 1 # dot index | |
a = inp.find("(") - 2 # repetitive decimals init index -> '(' | |
inp = inp.replace("(", "").replace(")", "").replace(".", "") | |
num = 0 | |
den = 0 | |
if inp.isdigit(): | |
if dot >= 0: | |
if a >= 0: | |
ntimes = 1 | |
diff = abs(a - dot) | |
if diff > 1: # Convert non repetitive decimal to integer side | |
a = dot + diff | |
ntimes = pow(10, diff) | |
intpart_s = inp[:a+1] # integer part (str) | |
decpart_s = inp[a+1:] # repetitive decimal part (str) | |
intpart = stoi(intpart_s) # integer part (int) | |
decpart = stoi(decpart_s) # repetitive decimal part (int) | |
exp = pow(10, len(decpart_s)) # 10^(non repetitive decimal places) | |
num = intpart * exp + decpart - intpart | |
den = int_repeat(9, len(decpart_s)) * ntimes | |
else: | |
intpart_s = inp[:dot+1] # integer part (str) | |
decpart_s = inp[dot+1:] # decimal part (str) | |
intpart = stoi(intpart_s) # integer part (int) | |
decpart = stoi(decpart_s) # decimal part (int) | |
exp = pow(10, len(intpart_s)) # 10^(integer places) | |
num = intpart * exp + decpart | |
den = exp | |
elif dot < 0: | |
num = int(inp) | |
den = 1 | |
else: | |
err(1) | |
gcd_num_den = gcd(num, den) | |
if gcd_num_den == 1: | |
print("{num}/{den} = {res}\n".format(num=num, den=den, res=num/den)) | |
else: | |
num_s = num // gcd_num_den # numerator simplified | |
den_s = den // gcd_num_den # denominator simplified | |
print("{num_s}/{den_s} = {num}/{den} = {res}\n".format(num=num, den=den, res=num/den, | |
num_s=num_s, den_s=den_s)) |
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Usage: use (, ) to denote the repeating part.
Samples:
10.22(3) = 10.223333333333...
35.29(45) = 35.294545454545...