13. Roman to Integer LeetCode题解

Given a roman numeral, convert it to an integer.

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

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题意：

给定一个罗马数字，将其转换为整数。

输入数据范围从1到3999

题解：

罗马数字规则

根据规则，左减的数字有限制，仅限于I、X、C，且最多一位，该位小于其右侧的数字，

则只有在s[i] < s[i + 1]时才减去s[i]对应的值，否则加上s[i]对应的值

Code【Java】

public class Solution {
    static String str = "IVXLCDM";
    static int[] nums = {1, 5, 10, 50, 100, 500, 1000};
    public int romanToInt(String s) {
        int ans = 0;
        for (int i = 0; i < s.length() - 1; ++i) {
            int index = str.indexOf(s.charAt(i));
            int index2= str.indexOf(s.charAt(i + 1));
            ans += (index < index2) ? -nums[index] : nums[index];
        }
        ans += nums[str.indexOf(s.charAt(s.length() - 1))];
        return ans;
    }
}

Code【C++】

class Solution {
    string str = "IVXLCDM";
    int nums[7] = {1, 5, 10, 50, 100, 500, 1000};
public:
    int romanToInt(string s) {
        int ans = 0;
        for (int i = 0; i < s.length() - 1; ++i) {
            int index = str.find(s[i]);
            int index2= str.find(s[i + 1]);
            ans += (index < index2) ? -nums[index] : nums[index];
        }
        ans += nums[str.find(s[s.length() - 1])];
        return ans;
    }
};