LeetCode Roman to Integer, leetcoderoman

LeetCode Roman to Integer, leetcoderoman

Given a roman numeral, convert it to an integer.

Input is guaranteed to be within the range from 1 to 3999.

The meaning of the question is to convert the roman numerals into Arabic numerals.

Idea: After understanding the structure of the Roman numerals, you can proceed from the back to the front.

Class Solution {public: int romanToInt (string s) {if (s. size () = 0) return 0; map <char, int> mp; mp ['I'] = 1; mp ['V'] = 5; mp ['X'] = 10; mp ['l'] = 50; mp ['C'] = 100; mp ['D'] = 500; mp ['M'] = 1000; int len = s. size (); int sum = mp [s [len-1]; for (int I = len-2; I> = 0; I --) {if (mp [s [I] <mp [s [I + 1]) sum-= mp [s [I]; else sum + = mp [s [I];} return sum ;}};