leetcode 690

通过阅读题目就可以知道，这道题是通过dfs or bfs。

将所有的员工都放入到Map中，Map的key为员工的ID，value为员工的具体信息。

bfs：（Java 1.8）

public int bfs(List<Employee> employees, int id) {
        Queue<Employee> queue = new LinkedList<>();
        Map<Integer, Employee> map = employees.stream().collect(
                Collectors.toMap(Employee::getId,
                        employee -> employee,
                        (o, o2) -> o));
        queue.offer(map.get(id));
        int importantSum = 0;
        while (!queue.isEmpty()) {
            int size = queue.size();
            for (int i=0; i<size; i++) {
                Employee poll = queue.poll();
                importantSum += poll.importance;
                if (poll.subordinates.size() != 0) {
                    for (Integer sub : poll.subordinates) {
                        queue.offer(map.get(sub));
                    }
                }
            }
        }
        return importantSum;
    }

dfs：

public int dfs(List<Employee> employees, int id) {
        Map<Integer, Employee> map = new HashMap<>();
        for (Employee employee : employees) {
            map.put(employee.id, employee);
        }
        Employee employee = map.get(id);
        int sum = getDfsNum(map, id);

        return sum;
    }
    public int getDfsNum(Map<Integer, Employee> map, int k) {
        int sum = 0;
        sum += map.get(k).importance;
        if (map.get(k).subordinates.size() == 0) {
            return sum;
        } else {
            for (Integer sub : map.get(k).subordinates) {
                sum += getDfsNum(map, sub);
            }
        }
        return sum;
    }

根据答案修改之后：

public int dfs(List<Employee> employees, int id) {
        Map<Integer, Employee> map = new HashMap<>();
        for (Employee employee : employees) {
            map.put(employee.id, employee);
        }
        Employee employee = map.get(id);
        int sum = getDfsNum(map, id);

        return sum;
    }
    public int getDfsNum(Map<Integer, Employee> map, int k) {
        int sum = map.get(k).importance;;
        for (Integer sub : map.get(k).subordinates) {
            sum += getDfsNum(map, sub);
        }
        return sum;
    }