Add Solution3.java to problems 0690

Author: huaxu1024

solution/0690. Employee Importance/Solution3.java

@@ -0,0 +1,34 @@
+/*
+// Employee info
+class Employee {
+    // It's the unique id of each node;
+    // unique id of this employee
+    public int id;
+    // the importance value of this employee
+    public int importance;
+    // the id of direct subordinates
+    public List<Integer> subordinates;
+};
+*/
+
+import java.util.*;
+
+class Solution {
+    public int getImportance(List<Employee> employees, int id) {
+        Map<Integer, Employee> map = new HashMap<>();
+        for (Employee employee : employees) {
+            map.put(employee.id, employee);
+        }
+        Stack<Employee> stack = new Stack<>();
+        stack.add(map.get(id));
+        int ant = 0;
+        while (!stack.isEmpty()) {
+            Employee pop = stack.pop();
+            ant += pop.importance;
+            for (Integer subordinate : pop.subordinates) {
+                stack.add(map.get(subordinate));
+            }
+        }
+        return ant;
+    }
+}