leetcode-13-字符串题-罗马数字转整数

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题目

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解法

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class Solution {
public:
    int romanToInt(string s) {
        if(s.empty()) return 0;

        unordered_map<char, int> hasher{{'I', 1},{'V', 5},{'X', 10},{'L', 50},{'C', 100},{'D', 500},{'M', 1000}};

        int res = 0;
        for(int i = 0; i < s.size(); ++i){
            bool condition = (i+1 < s.size()) && (s[i] == 'I' && (s[i+1] == 'V' || s[i+1] == 'X')) || (s[i] == 'X' && (s[i+1] == 'L' || s[i+1] ==  'C')) || (s[i] == 'C' && (s[i+1] == 'D' || s[i+1] == 'M'));
            
            if(condition){
                res += hasher[s[i+1]] - hasher[s[i]];
                ++i;
            }else{
                res += hasher[s[i]];
            }
        }

        return res;
    }
};