leetcode刷题笔记十二 整数转罗马数字 Scala版本

leetcode刷题笔记十二 整数转罗马数字 Scala版本

源地址：整数转罗马数字

问题描述：

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.

简要思路分析：

本体思路较为简单，将各个进制位上的罗马字母写入val中，通过对目标数对千百十进制位进行整除与取余，再将各个进制上的结果拼接返回即可。

代码补充：

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