# LeetCode No.13 Roman to Integer
**[題目連結](https://leetcode.com/problems/roman-to-integer/)**
花比較多時間去思考**I,X,C要減一**的規則，約10~15分鐘
## JavaScript
```javascript=
/**
* @param {string} s
* @return {number}
*/
var romanToInt = function(s) {
var num = 0;
romanDict = {
'I':1,
'V':5,
'X':10,
'L':50,
'C':100,
'D':500,
'M':1000
}
for (var i = 0 ;i < s.length;i++){
var roman = s[i]
if (i==s.length-1){
num += romanDict[roman];
}
else if (roman=== 'I' && (s[i+1]==='V'||s[i+1]==='X')){
num -= romanDict[roman];
}
else if (roman=== 'X' && (s[i+1]==='L'||s[i+1]==='C')){
num -= romanDict[roman];
}
else if (roman=== 'C' && (s[i+1]==='D'||s[i+1]==='M')){
num -= romanDict[roman];
}
else{
num += romanDict[roman];
}
}
return num;
};
```
## Python
```python=
```