diff --git a/Problem 1.sql b/Problem 1.sql
new file mode 100644
index 0000000..941f8dd
--- /dev/null
+++ b/Problem 1.sql	
@@ -0,0 +1 @@
+select score, dense_rank() over (order by score desc) as 'rank' from Scores
\ No newline at end of file
diff --git a/Problem 2.sql b/Problem 2.sql
new file mode 100644
index 0000000..71c78ec
--- /dev/null
+++ b/Problem 2.sql	
@@ -0,0 +1,8 @@
+select (
+    case
+        when mod(id, 2) != 0 and id != cnt then id + 1
+        when mod(id, 2) != 0 and id = cnt then id
+        else id - 1
+    end
+) AS 'id', student from Seat, (select count(*) as cnt from Seat) AS seat_cnt
+order by id;
\ No newline at end of file
diff --git a/Problem 3.sql b/Problem 3.sql
new file mode 100644
index 0000000..9b73a7d
--- /dev/null
+++ b/Problem 3.sql	
@@ -0,0 +1,6 @@
+select id, (
+    case
+        when isnull(p_id) then 'Root'
+        when id in (select distinct p_id from Tree) then 'Inner'
+        else 'Leaf'
+    end) as type from Tree
\ No newline at end of file
diff --git a/Problem 4.sql b/Problem 4.sql
new file mode 100644
index 0000000..b92d89e
--- /dev/null
+++ b/Problem 4.sql	
@@ -0,0 +1,8 @@
+with cte as (
+    select d.name as Department, e.name as Employee, e.salary as Salary,
+    dense_rank() over (partition by d.name order by Salary desc) as rnk
+    from Employee e
+    left join Department d on d.id = e.departmentId
+)
+
+select Department, Employee, Salary from cte where rnk <= 3
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