Roman numerals are represented by seven different symbols:
**Symbol** **Value** I 1 V 5 X 10 L 50 C 100 D 500 M 1000
2 is written as
II in Roman numeral, just two one's added together.
12 is written as
XII, which is simply
X + II. The number
27 is written as
XXVII, which is
XX + V + II.
Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not
IIII. Instead, the number four is written as
IV. Because the one is before the five we subtract it making four. The same principle applies to the number nine, which is written as
IX. There are six instances where subtraction is used:
Ican be placed before
X(10) to make 4 and 9.
Xcan be placed before
C(100) to make 40 and 90.
Ccan be placed before
M(1000) to make 400 and 900.
Given an integer, convert it to a roman numeral.
Input: num = 3 Output: "III"
Input: num = 4 Output: "IV"
Input: num = 9 Output: "IX"
Input: num = 58 Output: "LVIII" Explanation: L = 50, V = 5, III = 3.
Input: num = 1994 Output: "MCMXCIV" Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
1 <= num <= 3999
First of all, we're going to create a
map with all possible Roman-Integer pairs.
The algorithm is going through this
map from biggest to smallest starting from
I and keeping track of a
The main algorithm is using the division
map[key] and modulus operator. The division tells us how many particular symbols do we need to repeat. And the modulus operator helps us to change the
The easiest way to understand this solution is to look at an example :) Let's imagine we need to convert
In this solution, we can do some improvements:
We can return the result if the num equals
We can check whether the division equals
0or not, if not we don't need to repeat anything
The time complexity is going to be
O(n), there is
n is the number of Roman numeral characters. And the space complexity is
Hope it was useful for you!
Thanks for reading!