diff --git a/Problem 1.sql b/Problem 1.sql
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--- /dev/null
+++ b/Problem 1.sql	
@@ -0,0 +1,4 @@
+# Write your MySQL query statement below
+
+select score,dense_rank() over(order by score desc) as 'rank'
+from scores;
diff --git a/Problem 2.sql b/Problem 2.sql
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+++ b/Problem 2.sql	
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+# Write your MySQL query statement below
+select 
+case 
+        when id%2 =1  and  id+1 <= (select count(*) from Seat) then id+1
+        when id%2 =0  then id-1 
+        else id
+end as id,student
+from Seat
+order by id asc;
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diff --git a/Problem 3.sql b/Problem 3.sql
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+++ b/Problem 3.sql	
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+# Write your MySQL query statement below
+select id,
+case
+    when p_id is null then 'Root'
+    when id in (select 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
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--- /dev/null
+++ b/Problem 4.sql	
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+# Write your MySQL query statement below
+
+with cte as(
+    select e.id,e.name as Employee,e.salary as Salary,d.name as Department,dense_rank() over(partition by d.   name order by e.salary desc) as dens_col
+    from employee e
+    join Department d on e.departmentId = d.id)
+    
+    select Department,Employee,Salary
+    from cte
+    where dens_col <=3;
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