942. DI String Match

class Solution {
public:
    vector<int> diStringMatch(string S) {
        
        int size= S.size();
        int low=0;
        int high=size;
        
        vector<int> arr(size+1);
        
        for(int i=0; i<size; i++){
            
            if(S[i]=='I'){
                
                arr[i]=low;
                low++;
                
            }
            else{
                
                arr[i]=high;
                high--;
                
            }
        }
        
        arr[size]=low;
        
        return arr;
    }
};