Common Denominators
Codewars Kata 17√
Description
Link: convertFracts
-简述：本题以列表形式给定一些分数的分子和分母组合值，要求将各分数转换为分母相等的形式。
-思路：求出所有分母的最小公倍数。
-难点：1 模块导入和列表推导式表达。
You will have a list of rationals in the form { {numer_1, denom_1} , … {numer_n, denom_n} } or [ [numer_1, denom_1] , … [numer_n, denom_n] ] or [ (numer_1, denom_1) , … (numer_n, denom_n) ] where all numbers are positive ints.
You have to produce a result in the form (N_1, D) … (N_n, D) or [ [N_1, D] … [N_n, D] ] or [ (N_1’, D) , … (N_n, D) ] or { {N_1, D} … {N_n, D} } depending on the language (See Example tests) in which D is as small as possible and N_1/D == numer_1/denom_1 … N_n/D == numer_n,/denom_n.
Example:
convertFracs [(1, 2), (1, 3), (1, 4)] should be [(6, 12), (4, 12), (3, 12)]
Note for Bash
input is a string, e.g “2,4,2,6,2,8”
output is then “6 12 4 12 3 12”
My solution
from functools import reduce
from math import gcd
def get_lcm(lst):
return reduce(lambda a,b: a * b // gcd(a, b),lst)
def convertFracts(lst):
my_gcd = reduce(gcd,[i[0]+i[1] for i in lst])
my_lcm = get_lcm([i[1]//my_gcd for i in lst])
return [[i[0]*my_lcm//i[1],my_lcm] for i in lst]
a = [[2,4], [2, 6], [2, 8]]
print(convertFracts(a))
# 根据题目描述 当输入为”2,4,2,6,2,8”时，输出依然为"6 12 4 12 3 12”，测试符合要求。
Given solutions:
from fractions import gcd
def get_lcm(lst):
return reduce(lambda x, y : x*y/gcd(x,y), lst)
def convertFracts(lst):
lcm = get_lcm([ y for x, y in lst])
return [ [x*lcm/y, lcm] for x, y in lst]
Points:
1 求最大公约数的方法：辗转相除法，也叫欧几里得算法。
2 reduce函数：对参数序列中元素进行累积。reduce(function, iterable[, initializer])
3 根据题目描述 当输入为”2,4,2,6,2,8”时，输出依然为”6 12 4 12 3 12”，测试符合要求。
4 gcd函数原来是从fractions模块导入，现在变为从math模块导入。
