Seven different symbols represent Roman numerals with the following values:
| Symbol |
Value |
| I |
1 |
| V |
5 |
| X |
10 |
| L |
50 |
| C |
100 |
| D |
500 |
| M |
1000 |
Roman numerals are formed by appending the conversions of decimal place values from highest to lowest. Converting a decimal place value into a Roman numeral has the following rules:
- If the value does not start with 4 or 9, select the symbol of the maximal value that can be subtracted from the input, append that symbol to the result, subtract its value, and convert the remainder to a Roman numeral.
- If the value starts with 4 or 9 use the subtractive form representing one symbol subtracted from the following symbol, for example, 4 is 1 (
I) less than 5 (V): IV and 9 is 1 (I) less than 10 (X): IX. Only the following subtractive forms are used: 4 (IV), 9 (IX), 40 (XL), 90 (XC), 400 (CD) and 900 (CM).
- Only powers of 10 (
I, X, C, M) can be appended consecutively at most 3 times to represent multiples of 10. You cannot append 5 (V), 50 (L), or 500 (D) multiple times. If you need to append a symbol 4 times use the subtractive form.
Given an integer, convert it to a Roman numeral.
Example 1:
Input: num = 3749
Output: "MMMDCCXLIX"
Explanation:
3000 = MMM as 1000 (M) + 1000 (M) + 1000 (M)
700 = DCC as 500 (D) + 100 (C) + 100 (C)
40 = XL as 10 (X) less of 50 (L)
9 = IX as 1 (I) less of 10 (X)
Note: 49 is not 1 (I) less of 50 (L) because the conversion is based on decimal places
Example 2:
Input: num = 58
Output: "LVIII"
Explanation:
50 = L
8 = VIII
Example 3:
Input: num = 1994
Output: "MCMXCIV"
Explanation:
1000 = M
900 = CM
90 = XC
4 = IV
Constraints:
## Solution(Python)
```Python
class Solution:
def __init__(self):
self.mapping = [(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 intToRoman(self, num: int) -> str:
# num = 3749
# 3000 =? MMM
# 700 = 500 + 100 + 100 = DCC
# 40 = XL = 50 - 10
# 9 = IX = 10 - 9
#
# create hashmap of all values
# orderelsist = largest to smallest
#
# res
# num = 3748
# condition: num >0
# loop ordered element
# condition num > orderedelement
# break
# num = 3748 [(1000 , m ) () (500, D)....]
# res = ""
# 3748 > 0
# -> loop
# 3748 >= 1000
# -> while 3748 > 1000
# 3748 - 1000 = 3
# res += M
# num = 3728 % 1000 = 728
# 748 > 0
# -> loop
# 748 > 1000 f
# 748 > 500 t
# while 748 >= 500
# 748 - 500 = 248
#
# res += 3*D
# num = 748 % 500 =
# simple algorith m
# while num >= mapped value:
# append the reuslt
# num -= mapped value
roman = ''
while num > 0: # 2749
for (value, symbol) in self.mapping:
while num >= value: # 2749 > 1000
roman += symbol # MM
num -= value # 2749
return roman
```