旅行终点站

实现代码：

public String destCity(List<List<String>> paths) {
        List<String> startStaion = new ArrayList<String>();
        List<String> endStaion = new ArrayList<String>();
        for(List<String> list:paths){
            startStaion.add(list.get(0));
            endStaion.add(list.get(1));
        }
        for(String end:endStaion){
            if(!startStaion.contains(end)){
                return end;
            }
        }
        return null;
    }