面试题求解答

[朝霞清辉]

@Data
class Key {
    private String k;
    private List<Key> list;
}
public class Test {
    public static void main(String[] args) {
        List<String> strList = Arrays.asList(
                "信息部,IT组,张三",
                "信息部,IT组,李四",
                "信息部,运维组,王五",
                "科技部,研发组,赵六");
        List<Key> list = new ArrayList<>();

        // TODO 请填写此处代码

        System.out.println(JSON.toJSONString(list));
    }
}

要求如下：

引用

输出结果（为了方便区分结构，我们对JSON串进行了换行）：

[
  {
    "k": "信息部",
    "list": [
      {
        "k": "IT组",
        "list": [
          {
            "k": "张三"
          },
          {
            "k": "李四"
          }
        ]
      },
      {
        "k": "运维组",
        "list": [
          {
            "k": "王五"
          }
        ]
      }
    ]
  },
  {
    "k": "科技部",
    "list": [
      {
        "k": "研发组",
        "list": [
          {
            "k": "赵六"
          }
        ]
      }
    ]
  }
]

[ITjavaman]

    public static void main(String[] args) {
        List<String> strList = Arrays.asList(
                "信息部,IT组,张三",
                "信息部,IT组,李四",
                "信息部,运维组,王五",
                "科技部,研发组,赵六");
        List<Key> list = new ArrayList<>();

        // TODO 请填写此处代码
        String[] split = null;
        for(String str:strList){
            split = str.split(",");
            f(0,split,list);
        }
        System.out.println(JSON.toJSONString(list));
    }

    private static void f(int i,String [] split,List<Key> list){
        Key key = null;
        if(i==split.length){
            key = getKey(split[i-1], list);
            if(null != key){
                key.setList(null);
            }
            return;
        }
        if(null == list){
            list = new ArrayList<>();
        }
        key = getKey(split[i], list);
        if(null == key){
            key = new Key();
            key.setK(split[i]);
            key.setList(new ArrayList<>());
            list.add(key);
        }
        f(i+1,split,key.getList());
    }

    private static Key getKey(String keyStr,List<Key> list){
        for (int i=0;i<list.size();i++){
            if(list.get(i).getK().equals(keyStr)){
                return list.get(i);
            }
        }
        return null;
    }

[朝霞清辉]

引用 1 楼 ITjavaman 的回复:

    public static void main(String[] args) {
        List<String> strList = Arrays.asList(
                "信息部,IT组,张三",
                "信息部,IT组,李四",
                "信息部,运维组,王五",
                "科技部,研发组,赵六");
        List<Key> list = new ArrayList<>();

        // TODO 请填写此处代码
        String[] split = null;
        for(String str:strList){
            split = str.split(",");
            f(0,split,list);
        }
        System.out.println(JSON.toJSONString(list));
    }

    private static void f(int i,String [] split,List<Key> list){
        Key key = null;
        if(i==split.length){
            key = getKey(split[i-1], list);
            if(null != key){
                key.setList(null);
            }
            return;
        }
        if(null == list){
            list = new ArrayList<>();
        }
        key = getKey(split[i], list);
        if(null == key){
            key = new Key();
            key.setK(split[i]);
            key.setList(new ArrayList<>());
            list.add(key);
        }
        f(i+1,split,key.getList());
    }

    private static Key getKey(String keyStr,List<Key> list){
        for (int i=0;i<list.size();i++){
            if(list.get(i).getK().equals(keyStr)){
                return list.get(i);
            }
        }
        return null;
    }

谢谢

[qybao]

简单的for循环就可以了

public class Test {
    public static void main(String[] args) {
        List<String> strList = Arrays.asList(
                "信息部,IT组,张三",
                "信息部,IT组,李四",
                "信息部,运维组,王五",
                "科技部,研发组,赵六");
        List<Key> list = new ArrayList<>();
        
        // TODO 请填写此处代码
        for (String s : strList) { //字符串list循环
            String[] arr = s.split(","); //字符串分割
            List<Key> ll = list;
            for (int i=0; i<arr.length; i++) { //分别判断分割后的字符串在结果list的k是否存在
                Key key = null;
                for (Key k : ll) {
                    if (arr[i].equals(k.getK())) {
                        key = k;
                        break;
                    }
                }
                if (key == null) { //如果不存在，new一个Key放到结果list里
                    key = new Key();
                    key.setK(arr[i]);
                    ll.add(key);
                    for (int j=i+1; j<arr.length; j++) { //其实主要就是循环生成list
                        ll = new ArrayList<>();
                        key.setList(ll);
                        key = new Key();
                        key.setK(arr[j]);
                        ll.add(key);
                    }
                    break;
                }
                ll = key.getList(); //如果存在，继续判断key.list里是否存在下一个分割的字符串
                if (ll == null) {
                    ll = new ArrayList<>();
                    key.setList(ll);
                }
            }
        }
        
        System.out.println(JSON.toJSONString(list));
    }
}