Roman Number to Integer

Question – Given a string in roman no format (s)  your task is to convert it to an integer. Various symbols and their values are given below.
I 1
V 5
X 10
L 50
C 100
D 500
M 1000

Example

Give Input: s = V Expected Output: 5

Logic

• Create a Hashmpa to store corresponding values
• Iterate over the string and compare the current character with the next one, so it’s greater than adding it to the sum otherwise need to subtract it.
• The last character is let un touched so we are adding in the last.
• Finally, return the sum.

Code

class Solution {
    
    public int romanToDecimal(String str) {
        // code here
        HashMap<Character,Integer>hm=new HashMap<>();
        hm.put('I',1);
        hm.put('V',5);
        hm.put('X',10);
        hm.put('L',50);
        hm.put('C',100);
        hm.put('D',500);
        hm.put('M',1000);
        
        char arr[]=str.toCharArray();
        int sum=0;
        for(int i=0;i<arr.length-1;i++){
            if(hm.get(arr[i])>=hm.get(arr[i+1])){
                sum+=hm.get(arr[i]);
            }else{
                sum-=hm.get(arr[i]);
            }
        }
        sum+=hm.get(arr[arr.length-1]);
        return sum;
    }
}