> For the complete documentation index, see [llms.txt](https://hao-fu-1.gitbook.io/oj/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hao-fu-1.gitbook.io/oj/math/roman-to-integer/integer-to-roman.md).

# Integer to Roman

<https://leetcode.com/problems/integer-to-roman/description/>

> Given an integer, convert it to a roman numeral.
>
> Input is guaranteed to be within the range from 1 to 3999.

## Thoughts

本质上是不断除10, 把每一位映射回去. 只是千, 百, 十都有各自的映射.

## Code

```
class Solution {
    public String intToRoman(int num) {
        String M[] = {"", "M", "MM", "MMM"};
        String C[] = {"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"};
        String X[] = {"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"};
        String I[] = {"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"};
        return M[num / 1000] + C[(num % 1000) / 100] + X[(num % 100) / 10] + I[num % 10];
    }
}
```

## Analysis

时空复杂度O(1).