# Question

Formatted question description: https://leetcode.ca/all/12.html

```
12. Integer to Roman
Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.
Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1000
For example, two is written as II in Roman numeral, just two one's added together.
Twelve is written as, XII, which is simply X + II. The number twenty seven 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:
I can be placed before V (5) and X (10) to make 4 and 9.
X can be placed before L (50) and C (100) to make 40 and 90.
C can be placed before D (500) and M (1000) to make 400 and 900.
Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.
Example 1:
Input: 3
Output: "III"
Example 2:
Input: 4
Output: "IV"
Example 3:
Input: 9
Output: "IX"
Example 4:
Input: 58
Output: "LVIII"
Explanation: L = 50, V = 5, III = 3.
Example 5:
Input: 1994
Output: "MCMXCIV"
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
@tag-string
```

# Algorithm

Because the range of input numbers (1-3999) is limited in the question, the question becomes much simpler.

I-1

V-5

X-10

L-50

C-100

D-500

M-1000

For example, the Roman numeral for the integer 1437 is MCDXXXVII. It is not difficult to find that the thousands, hundreds, tens, and ones digits are represented by Roman numerals. 1000-M, 400-CD, 30-XXX, 7-VII. So what we have to do is to use the quotient method to extract the numbers in each digit, and then express them separately:

100-C

200-CC

300-CCC

400-CD

500-D

600-DC

700-DCC

800-DCCC

900-CM

Can be divided into four categories, 100 to 300 category, 400 category, 500 to 800 category, 900 last category. The situation on digit is similar.

# Code

Java