问题描述
是数字“ a”,“ b”和“ c”:
a = 77033412951888085
b = a - 5
c = 2840988860479
一个部门产生以下结果
>>> a/c,b/c
(27115.0,27115.0)
尝试解决a CodeWars' Kata,我需要计算a = 14949283383840498 * 27115 / 5262)
但是,不是得到
77033412951888085
我明白了
7.703341295188808e+16
...这只是...,但有点错误,叹了口气。 但这足以阻止我通过,这是错误的,因为它被解释为 77033412951888080 。还有...
>>> 14949283383840498 * 27115 / 5262 == 77033412951888085
False
编辑:
由于@GreenCloakGuy的注释解决了我的问题(如图所示),所以我决定添加实际的代码(和测试),因为给定的解决方案对我不起作用。我正在使用Python 3.8.6
import functools
def gcd(a:int,b:int) -> int:
'Recursive function to return gcd of a and b'
if a == 0:
return b
return gcd(b % a,a)
def lcm(a:int,b:int) -> int:
'Function to return LCM of two numbers'
return a / gcd(a,b) * b
def convertFracts(fractions:list) -> list:
if len(fractions) == 0:
return []
denominators = [i[1] for i in fractions]
LCM = functools.reduce(lambda a,b: lcm(a,b),denominators)
# Here I attempt so use @GreenCloakGuy 's solution,and use floor division.
return [[num * LCM // den,LCM] for num,den in fractions]
import unittest
class TestSolution(unittest.TestCase):
#@unittest.skip
def test_sample(self):
a = [[1,2],[1,3],4]]
b = [[6,12],[4,[3,12]]
self.assertEqual(convertFracts(a),b)
@staticmethod
def simplifyFractions(result: list):
for numerator,denominator in result:
GCD = gcd(numerator,denominator)
yield [numerator/GCD,denominator/GCD]
@unittest.expectedFailure
def test_failed(self):
#Test result I got problems with
test_result = [[77033412951888085,14949283383840498],[117787497858828,[2526695441399712,14949283383840498]
]
#Infer initial simplified fractions
starting_fractions = [fraction for fraction in self.simplifyFractions(test_result)]
print('Infered starting fractions: ',starting_fractions)
my_result = convertFracts(starting_fractions)
print('My result: ',my_result)
my_result_as_int = list(map(lambda x: [int(x[0]),int(x[1])],convertFracts(my_result)))
print('My result as int: ',my_result_as_int)
self.assertEqual(test_result,my_result_as_int)
解决方法
使其工作的两种方法:
- 正确使用整数除法(感谢@GreenCloakGuy和@MarkDickinson)
- 使用十进制。十进制。可能是this question 的副本
十进制为我工作。这是更新的代码(仅导入和更新的函数):
正确使用//
import functools
#def gcd
def lcm(a:int,b:int) -> int:
'Function to return LCM of two numbers'
return a // gcd(a,b) * b
def convertFracts(fractions:list) -> list:
if len(fractions) == 0:
return []
denominators = [i[1] for i in fractions]
least_common_multiple = functools.reduce(lambda a,b: lcm(a,b),denominators)
return [[num * least_common_multiple // den,least_common_multiple] for num,den in fractions]
使用十进制:
import functools
from decimal import Decimal
#def gcd
def lcm(a:int,b) * b
def convertFracts(fractions:list) -> list:
if len(fractions) == 0:
return []
denominators = [i[1] for i in fractions]
least_common_multiple = Decimal(functools.reduce(lambda a,denominators))
return [[Decimal(num) * least_common_multiple / Decimal(den),den in fractions]
如果lcm
使用浮点除法,十进制也可以使用,但是我认为我还是可以解决这个问题,