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, 2
is written as II
in Roman numeral, just two ones 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:
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: s = "III"
Output: 3
Explanation: III = 3.
Input: s = "LVIII"
Output: 58
Explanation: L = 50, V= 5, III = 3.
Input: s = "MCMXCIV"
Output: 1994
Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
1 <= s.length <= 15
s
contains only the characters ('I', 'V', 'X', 'L', 'C', 'D', 'M')
.[1, 3999]
.var romanToInt = function(s) {
const nums = {"I" : 1, "V" : 5, "X" : 10, "L" : 50, "C" : 100, "D" : 500, "M" : 1000};
let ans = 0;
for (let i = 0; i < s.length ; i++) {
if(nums[s[i]] < nums[s[i+1]]) {
ans -= nums[s[i]];
} else ans += nums[s[i]];
}
return ans;
};
nums 객체에 로마자 문자열값을 key로 해당하는 숫자를 value로 저장한 후 s의 index 순서대로 key에 따른 value값을 더해주었다. 단 그 다음 문자가 앞문자보다 큰 값을 가지면 빼라는 의미이므로 if문을 통해 처리해주었다.