1233. Remove Sub-Folders from the Filesystem

class Solution {
public:
    vector<string> removeSubfolders(vector<string>& folder) {
        vector<string>ans;
        sort(folder.begin(), folder.end());
        string prev = "a";     //Random

        for(int i=0; i<folder.size(); ++i){
            if(folder[i].size()>=prev.size()){
                if(folder[i].substr(0,prev.size()) != prev || folder[i][prev.size()]!='/'){
                    ans.push_back(folder[i]);
                    prev = folder[i];
                }
            }
            else{
                ans.push_back(folder[i]);
                prev = folder[i];
            }
        }
        return ans;
    }
};