# 0012. Integer to Roman

https://leetcode.com/problems/integer-to-roman

## Description

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, `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:

* `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.

**Example 1:**

```
**Input:** num = 3
**Output:** "III"
```

**Example 2:**

```
**Input:** num = 4
**Output:** "IV"
```

**Example 3:**

```
**Input:** num = 9
**Output:** "IX"
```

**Example 4:**

```
**Input:** num = 58
**Output:** "LVIII"
**Explanation:** L = 50, V = 5, III = 3.
```

**Example 5:**

```
**Input:** num = 1994
**Output:** "MCMXCIV"
**Explanation:** M = 1000, CM = 900, XC = 90 and IV = 4.
```

**Constraints:**

* `1 <= num <= 3999`

## ac

```java
```
