I don't understand this code plz explain me

Question

num_map = [(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')]

def num2roman(num):

roman = ''

while num > 0:
for i, r in num_map:
while num >= i:
roman += r
num -= i

return roman

# test
print(num2roman(3000009))

Answer 1

What's the expected output?

Answer 2

I'm not really sure how to go about doing that, but I'm pretty sure that place value plays a large role, and perhaps you could split the number into different chunks..? I'm sorry not of much help-

Answer 3

No problem you tried to help me I really appreciate it

Answer 4

Shahir

Let's understand just for small number like 3000

So there are 3 loop while, for and while
Also you have an array containing tuples.

So let's for 3000

while num > 0 will be True so for loop will execute where we are taking key and value of each tuples from the aray.

Now we have i = 1000 and r = 'M'
So 3000 >= 1000 is True so while loop will execute and roman = roman + r = M

But now num = num - i = 3000 - 1000 = 2000

So now while 2000 >= 1000 which is True and in this case roman = roman + r = 'M' + 'M' = MM

Remember previous roman was M so new Roman is MM

Now again num = num - i = 2000 - 1000 = 1000

Now again while 1000 >= 1000 is True so again roman will be MMM

But now num will be 0 because of 1000 - 1000 = 0 so now inner while loop will not execute because finally 'num' is 0 and outer loop will also be not execute because num > 0 is False

So finally result is MMM

Answer 5

Thanks nice explanation

Answer 6

Task is to convert a integer into a Roman number

Answer 7

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