ibm 面试+ oa

public String getAncestor(String input){
        HashMap<String, String> hashMap = new HashMap<>();

        String[] strSet = input.split(",");
        String target1 = strSet[strSet.length - 2];
        String target2 = strSet[strSet.length - 1];

        for(int i = 0; i < strSet.length - 2; i++){
            String[] item = strSet[i].split("->");
            String employee = item[1];
            String manager = item[0];
            hashMap.put(employee, manager);
        }

        HashSet<String> hashSet = new HashSet<>();

        String p1Manager = target1;
        String p2Manager = target2;
        while(hashMap.containsKey(p1Manager) || hashMap.containsKey(p2Manager)){
            if(hashMap.containsKey(p1Manager)){
                p1Manager = hashMap.get(p1Manager);
                if(!hashSet.add(p1Manager)) return p1Manager;
            }

            if(hashMap.containsKey((p2Manager))){
                p2Manager = hashMap.get(p2Manager);
                if(!hashSet.add(p2Manager)) return p2Manager;
            }
        }

        return "";//
    }