13. Roman to Integer

13. Roman to Integer
【思路】

• 按照字符罗马数字规则改变成数字就行；

int roman(char c) {
    switch(c) {
        case 'I':
            return 1;
        case 'V':
            return 5;
        case 'X':
            return 10;
        case 'L':
            return 50;
        case 'C':
            return 100;
        case 'D':
            return 500;
        case 'M':
            return 1000;
        default:
            return 0;
    }
}

int romanToInt(string s) {
    int sum = 0;
    int len = s.length();
    for(int i=0;i<len -1;i++)
    {  int cur = roman(s[i]), next = roman(s[i+1]);
        if(cur<next)
            sum+=-cur;
        else
            sum+=cur;
    }
    sum += roman(s[len -1]); //最低位
    return sum;
}