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Integer to Roman

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

Problem Description

Seven different symbols represent Roman numerals with the following values:

Symbol Value
I 1
V 5
X 10
L 50
C 100
D 500
M 1000

Roman numerals are formed by appending the conversions of decimal place values from highest to lowest. Converting a decimal place value into a Roman numeral has the following rules:

  1. If the value does not start with 4 or 9, select the symbol of the maximal value that can be subtracted from the input, append that symbol to the result, subtract its value, and convert the remainder to a Roman numeral.
  2. If the value starts with 4 or 9 use the subtractive form representing one symbol subtracted from the following symbol, for example, 4 is 1 (I) less than 5 (V): IV and 9 is 1 (I) less than 10 (X): IX. Only the following subtractive forms are used: 4 (IV), 9 (IX), 40 (XL), 90 (XC), 400 (CD) and 900 (CM).
  3. Only powers of 10 (I, X, C, M) can be appended consecutively at most 3 times to represent multiples of 10. You cannot append 5 (V), 50 (L), or 500 (D) multiple times. If you need to append a symbol 4 times use the subtractive form. Given an integer, convert it to a Roman numeral.

Example 1

Input: num = 3749
Output: "MMMDCCXLIX"

Explanation:

  • 3000 = MMM as 1000 (M) + 1000 (M) + 1000 (M)
  • 700 = DCC as 500 (D) + 100 (C) + 100 (C)
  • 40 = XL as 10 (X) less of 50 (L)
  • 9 = IX as 1 (I) less of 10 (X)

Note: 49 is not 1 (I) less of 50 (L) because the conversion is based on decimal places

Example 2

Input: num = 58
Output: "LVIII"

Example 3

Input: num = 1994
Output: "MCMXCIV"

Constraints

  • 1 <= num <= 3999