[LeetCode] Roman To Integer

문제

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

 

Approach

Hash map을 통한 구현. I, L, C일때 다음 글자가 뭔지 보고 숫자 정하는거만 처리해주면 되고

Hash map 선언할때 선언과 동시에 내용 넣어서 초기화하는게 선언 해놓고 나중에 추가하는거보다 빠르다.

 

Code

https://github.com/chi3236/algorithm/blob/master/LeetCode_RomanToInteger.cpp

chi3236/algorithm