diff --git a/non-overlapping-intervals/okyungjin.py b/non-overlapping-intervals/okyungjin.py
new file mode 100644
index 0000000000..5fc005fb25
--- /dev/null
+++ b/non-overlapping-intervals/okyungjin.py
@@ -0,0 +1,22 @@
+"""
+https://leetcode.com/problems/non-overlapping-intervals/
+
+Time: O(N log N), intervals 정렬
+Space: O(1)
+"""
+class Solution:
+    def eraseOverlapIntervals(self, intervals: List[List[int]]) -> int:
+        # end 오름차순 intervals 정렬
+        intervals.sort(key=lambda x: x[1])
+
+        # remove count
+        count = 0        
+        last_end = float('-inf')
+
+        for start, end in intervals:
+            if start >= last_end: # 구간 안 겹침
+                last_end = end
+            else: # 구간 겹침
+                count += 1
+            
+        return count
diff --git a/same-tree/okyungjin.py b/same-tree/okyungjin.py
new file mode 100644
index 0000000000..bb59f630a3
--- /dev/null
+++ b/same-tree/okyungjin.py
@@ -0,0 +1,35 @@
+"""
+https://leetcode.com/problems/same-tree/description/
+
+N: min(p노드수, q노드수)
+Time: O(N)
+Space: O(N)
+"""
+
+# Definition for a binary tree node.
+# class TreeNode:
+#     def __init__(self, val=0, left=None, right=None):
+#         self.val = val
+#         self.left = left
+#         self.right = right
+class Solution:
+    def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
+        queue = deque([(p, q)])
+
+        while queue:
+            node_p, node_q = queue.popleft()
+
+            if not node_p and not node_q:
+                continue
+
+            elif node_p and node_q:
+                if node_p.val == node_q.val: 
+                    queue.append((node_p.left, node_q.left))
+                    queue.append((node_p.right, node_q.right))
+                else:
+                    return False
+            
+            else:
+                return False
+
+        return True