From a51536d1cc24a0eccfd9a37a666b54fde6f385fb Mon Sep 17 00:00:00 2001
From: YOUNGJIN NA <120540450+ppxyn1@users.noreply.github.com>
Date: Sun, 11 Jan 2026 18:54:45 +0900
Subject: [PATCH 1/2] [:solved] 2 problems

---
 invert-binary-tree/ppxyn1.py             | 24 ++++++++++++++++++
 search-in-rotated-sorted-array/ppxyn1.py | 32 ++++++++++++++++++++++++
 2 files changed, 56 insertions(+)
 create mode 100644 invert-binary-tree/ppxyn1.py
 create mode 100644 search-in-rotated-sorted-array/ppxyn1.py

diff --git a/invert-binary-tree/ppxyn1.py b/invert-binary-tree/ppxyn1.py
new file mode 100644
index 0000000000..57da1f79c6
--- /dev/null
+++ b/invert-binary-tree/ppxyn1.py
@@ -0,0 +1,24 @@
+# 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
+
+# idea : dfs
+# Time Complexity : O(n)
+
+class Solution:
+    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
+        if root is None:
+            return None
+
+        tmp = root.left
+        root.left = root.right 
+        root.right = tmp
+
+        self.invertTree(root.left)
+        self.invertTree(root.right)
+        return root
+
+
diff --git a/search-in-rotated-sorted-array/ppxyn1.py b/search-in-rotated-sorted-array/ppxyn1.py
new file mode 100644
index 0000000000..3f5d480c29
--- /dev/null
+++ b/search-in-rotated-sorted-array/ppxyn1.py
@@ -0,0 +1,32 @@
+# idea : binary search
+# Time Complexity : O(log n)
+
+# Sorting is not allowed because it costs O(n log n), so we must handle it using binary search without sorting.
+# One way is to check where the sorted order is disrupted.
+
+class Solution:
+    def search(self, nums: List[int], target: int) -> int:
+        left, right = 0, len(nums)-1
+        
+        while left <= right:
+            mid = (left + right) // 2
+            
+            if nums[mid] == target:
+                return mid
+            
+            # left ~ mid is sorted
+            if nums[left] <= nums[mid]:
+                if nums[left] <= target < nums[mid]:
+                    right = mid - 1
+                else:
+                    left = mid + 1
+            
+            # mid ~ right is sorted
+            else:
+                if nums[mid] < target <= nums[right]:
+                    left = mid + 1
+                else:
+                    right = mid - 1
+        return -1
+
+

From 8a79bf3a329155237ac0975dbedaac0ee3fc01df Mon Sep 17 00:00:00 2001
From: YOUNGJIN NA <120540450+ppxyn1@users.noreply.github.com>
Date: Sun, 11 Jan 2026 19:01:17 +0900
Subject: [PATCH 2/2] [:fixed]

---
 search-in-rotated-sorted-array/ppxyn1.py | 2 --
 1 file changed, 2 deletions(-)

diff --git a/search-in-rotated-sorted-array/ppxyn1.py b/search-in-rotated-sorted-array/ppxyn1.py
index 3f5d480c29..be93bb55d0 100644
--- a/search-in-rotated-sorted-array/ppxyn1.py
+++ b/search-in-rotated-sorted-array/ppxyn1.py
@@ -14,14 +14,12 @@ def search(self, nums: List[int], target: int) -> int:
             if nums[mid] == target:
                 return mid
             
-            # left ~ mid is sorted
             if nums[left] <= nums[mid]:
                 if nums[left] <= target < nums[mid]:
                     right = mid - 1
                 else:
                     left = mid + 1
             
-            # mid ~ right is sorted
             else:
                 if nums[mid] < target <= nums[right]:
                     left = mid + 1