第 20 天的 Leetcode 要開始拉，那我們就開始吧 ─=≡Σ(((っ›´ω`‹ )っ！

今天要寫的題目是 Roman to Integer，顧名思義就是把羅馬數字轉換成一般常見的阿拉伯數字。

Example:

Input: s = "III"
Output: 3

Input: s = "IV"
Output: 4

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

困難的點是必須要去判斷像 IV 這種由兩個字組成的值。

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.

結尾

怕超過時間，先待補