Add solution #13

Author: JoshCrozier

solutions/0013-roman-to-integer.js

@@ -3,7 +3,8 @@
  * https://leetcode.com/problems/roman-to-integer/
  * Difficulty: Easy
  *
- * Roman numerals are represented by seven different symbols: `I`, `V`, `X`, `L`, `C`, `D` and `M`.
+ * Roman numerals are represented by seven different symbols: `I`, `V`, `X`,
+ * `L`, `C`, `D` and `M`.
  *
  * Symbol       Value
  * I            1
@@ -14,13 +15,15 @@
  * 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`.
+ * 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:
+ * 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.