Roman to Integer---罗马数字转换为十进制整数

Given a roman numeral, convert it to an integer.

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

解题思路,循环遍历罗马数字字符串,从后往前,字母换成对应的数字,如果这个数字小于它后边的数字,则减去,如果大于,则加上.与此题相对应的题目则是整数转换为罗马数字,思路相反.

var romanToInt = function(s) {    var romanIntJson = {"I":1,"V":5,"X":10,"L":50,"C":100,"D":500,"M":1000};    var intNum = 0;    for(var i=s.length-1;i>=0;i--){        if(!intNum){            intNum = romanIntJson[s[i]];            continue;        }        if(romanIntJson[s[i]] >= romanIntJson[s[i + 1]]){            intNum+= romanIntJson[s[i]];        }else{            intNum -= romanIntJson[s[i]];        }    }    return intNum;};