【codewars】Roman Numerals Encoder

instruction

Create a function taking a positive integer as its parameter and returning a string containing the Roman Numeral representation of that integer.

Modern Roman numerals are written by expressing each digit separately starting with the left most digit and skipping any digit with a value of zero. In Roman numerals 1990 is rendered: 1000=M, 900=CM, 90=XC; resulting in MCMXC. 2008 is written as 2000=MM, 8=VIII; or MMVIII. 1666 uses each Roman symbol in descending order: MDCLXVI.

Example:

my solution

def solution(n):
# TODO convert int to roman string
symbolArr = [["I","V"],["X","L"],["C","D"],["M"]]
strN = str(n).zfill(4)
symbol = "M"*int(strN[0])
for i in range(2,-1,-1):
valueArr = ["", symbolArr[i][0], symbolArr[i][0] + symbolArr[i][0],symbolArr[i][0] + symbolArr[i][0] + symbolArr[i][0], symbolArr[i][0] + symbolArr[i][1],symbolArr[i][1],symbolArr[i][1] + symbolArr[i][0], symbolArr[i][1] + symbolArr[i][0] + symbolArr[i][0],symbolArr[i][1] + symbolArr[i][0] + symbolArr[i][0] + symbolArr[i][0],symbolArr[i][0] + symbolArr[i + 1][0]]
symbol = symbol + valueArr[int(strN[(3-i)])]
return symbol

best solution from others

def solution(n):
roman_numerals = {1000: 'M', 900: 'CM', 500: 'D', 400: 'CD', 100: 'C', 90: 'XC', 50: 'L', 40: 'XL', 10: 'X',9: 'IX', 5: 'V', 4: 'IV', 1: 'I'}
roman_string = ''
for key in sorted(roman_numerals.keys(),reverse=True):
while n >= key:
roman_string += roman_numerals[key]
n -= key
return roman_string

技巧点

针对原表能够重新构造

Symbol Value

I 1

V 5

X 10

L 50

C 100

D 500

M 1,000

roman_numerals = {1000: ‘M’, 900: ‘CM’, 500: ‘D’, 400: ‘CD’, 100: ‘C’, 90: ‘XC’, 50: ‘L’, 40: ‘XL’, 10: ‘X’,9: ‘IX’, 5: ‘V’, 4: ‘IV’, 1: ‘I’}