From 865ed8deb5198d5f8c8038db9754dfc4d5ae77f9 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Mon, 22 Jun 2026 01:07:05 +0900
Subject: [PATCH 01/18] freemjstudio/two-sum

---
 two-sum/freemjstudio.py | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 two-sum/freemjstudio.py

diff --git a/two-sum/freemjstudio.py b/two-sum/freemjstudio.py
new file mode 100644
index 0000000000..c36de0f08d
--- /dev/null
+++ b/two-sum/freemjstudio.py
@@ -0,0 +1,13 @@
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        answer = []
+        hashmap = dict()
+        for i in range(len(nums)):
+            current_num = nums[i]
+            diff = target - current_num
+            if diff in hashmap.keys(): 
+                return [i, hashmap[diff]] 
+            hashmap[current_num] = i # store the index of current num
+        
+        return answer
+        
\ No newline at end of file

From 1a6de375f2d596b02d7c08c3584c2e389f7a326a Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 27 Jun 2026 16:38:18 +0900
Subject: [PATCH 02/18] freemjstudio: contains-duplicate (easy, python)

---
 contains-duplicate/freemjstudio.py | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 contains-duplicate/freemjstudio.py

diff --git a/contains-duplicate/freemjstudio.py b/contains-duplicate/freemjstudio.py
new file mode 100644
index 0000000000..bee8ade7ad
--- /dev/null
+++ b/contains-duplicate/freemjstudio.py
@@ -0,0 +1,6 @@
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        first = len(nums)
+        set_nums = set(nums)
+        second = len(set_nums)
+        return (first != second)
\ No newline at end of file

From 953117650d0c3fc4c75ccd15503f14b75bc43cde Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 27 Jun 2026 16:38:42 +0900
Subject: [PATCH 03/18] freemjstudio: contains-duplicate

---
 contains-duplicate/freemjstudio.py | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/contains-duplicate/freemjstudio.py b/contains-duplicate/freemjstudio.py
index bee8ade7ad..0273cbd4e3 100644
--- a/contains-duplicate/freemjstudio.py
+++ b/contains-duplicate/freemjstudio.py
@@ -1,6 +1,8 @@
 class Solution:
     def containsDuplicate(self, nums: List[int]) -> bool:
-        first = len(nums)
-        set_nums = set(nums)
+        first = len(nums) # O(1) : 리스트 객체는 이미 자기자신의 길이를 저장하고 있음 
+        set_nums = set(nums) # O(N)
         second = len(set_nums)
-        return (first != second)
\ No newline at end of file
+        return (first != second)
+
+# 시간 복잡도 : O(N)
\ No newline at end of file

From 370fe38dead4945f03001ca6800b1e397359f5fc Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sun, 28 Jun 2026 15:38:37 +0900
Subject: [PATCH 04/18] freemjstudio: top k frequent elements

---
 top-k-frequent-elements/freemjstudio.py | 29 +++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 top-k-frequent-elements/freemjstudio.py

diff --git a/top-k-frequent-elements/freemjstudio.py b/top-k-frequent-elements/freemjstudio.py
new file mode 100644
index 0000000000..184c87aeee
--- /dev/null
+++ b/top-k-frequent-elements/freemjstudio.py
@@ -0,0 +1,29 @@
+import heapq
+
+class Solution:
+    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+        answer = []
+        count = dict()
+        heap = []
+        if len(nums) <= 1: 
+            return nums
+        # O(N)    
+        for num in nums: 
+            count[num] = count.get(num, 0) + 1
+        
+        # heap 의 크기는 최대 k 로 제한함. 
+        # unique 한 M개의 숫자를 선형 순회 O(M)
+        for num, freq in count.items():
+            if len(heap) < k: 
+                heapq.heappush(heap, (freq, num))         # O(logK)
+            else: 
+                if heap[0][0] < freq:
+                    heapq.heappop(heap)         # O(logK)
+                    heapq.heappush(heap, (freq, num))         # O(logK)
+
+        for _ in range(k):
+            k, v = heapq.heappop(heap)
+            answer.append(v)
+
+        return answer 
+        

From db69654f98e5b21d05356c77480071fcc2fc747c Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Thu, 2 Jul 2026 00:42:35 +0900
Subject: [PATCH 05/18] =?UTF-8?q?liner=20=EC=A0=81=EC=9A=A9?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 contains-duplicate/freemjstudio.py | 2 +-
 two-sum/freemjstudio.py            | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/contains-duplicate/freemjstudio.py b/contains-duplicate/freemjstudio.py
index 0273cbd4e3..6048a3c5ea 100644
--- a/contains-duplicate/freemjstudio.py
+++ b/contains-duplicate/freemjstudio.py
@@ -5,4 +5,4 @@ def containsDuplicate(self, nums: List[int]) -> bool:
         second = len(set_nums)
         return (first != second)
 
-# 시간 복잡도 : O(N)
\ No newline at end of file
+# 시간 복잡도 : O(N)
diff --git a/two-sum/freemjstudio.py b/two-sum/freemjstudio.py
index c36de0f08d..a274028f5c 100644
--- a/two-sum/freemjstudio.py
+++ b/two-sum/freemjstudio.py
@@ -10,4 +10,3 @@ def twoSum(self, nums: List[int], target: int) -> List[int]:
             hashmap[current_num] = i # store the index of current num
         
         return answer
-        
\ No newline at end of file

From 4886e4ae81c553204d4fb777bee15d6f2e656ac8 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 4 Jul 2026 13:36:49 +0900
Subject: [PATCH 06/18] freemjstudio/3sum

---
 3sum/freemjstudio.py | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 3sum/freemjstudio.py

diff --git a/3sum/freemjstudio.py b/3sum/freemjstudio.py
new file mode 100644
index 0000000000..546a726a1a
--- /dev/null
+++ b/3sum/freemjstudio.py
@@ -0,0 +1,29 @@
+class Solution:
+    def threeSum(self, nums: list[int]) -> list[list[int]]:
+        answer = []
+        nums.sort() 
+    
+        for i in range(len(nums)):
+            # 중복된 원소가 있는 경우 똑같이 검사할 필요가 없으므로 건너뛴다.
+            if i > 0 and nums[i] == nums[i-1]:
+                continue 
+
+            left, right = i+1, len(nums) - 1
+
+            while left < right: 
+                total = nums[i] + nums[left] + nums[right]
+                if total == 0:
+                    answer.append([nums[i], nums[left], nums[right]])
+                    # left, right 포인터를 둘다 한칸씩 이동시켜 다음 조합을 검사한다.
+                    left += 1
+                    right -= 1
+
+                    # 중복된 원소가 있는 경우 같은 정답 조합을 방지한다 
+                    while left < right and nums[left] == nums[left -1]:
+                        left += 1
+
+                elif total < 0:
+                    left += 1
+                else: 
+                    right -= 1
+        return answer 
\ No newline at end of file

From 2f3e189469125e7364ca761dab3ca351f680af2d Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 4 Jul 2026 16:28:00 +0900
Subject: [PATCH 07/18] freemjstudio/climbing-stairs

---
 climbing-stairs/freemjstudio.py | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 climbing-stairs/freemjstudio.py

diff --git a/climbing-stairs/freemjstudio.py b/climbing-stairs/freemjstudio.py
new file mode 100644
index 0000000000..d0eb35cb40
--- /dev/null
+++ b/climbing-stairs/freemjstudio.py
@@ -0,0 +1,18 @@
+class Solution:
+    def climbStairs(self, n: int) -> int:
+        answer = 0 
+        if n == 1: # ways(1) = 1
+            return 1
+
+        if n == 2: # ways(2) = 2
+            return 2
+        
+        dp = [0] * 46 # 1 <= n <= 45
+        dp[1] = 1
+        dp[2] = 2
+
+        # 점화식 : ways(n) = ways(n-1) + ways(n-2)
+        for i in range(3, n+1):
+            dp[i] = dp[i-1] + dp[i-2]
+        return dp[n]
+        
\ No newline at end of file

From 4c68b30f26cdc62100ba69972eb9f332a762c8ed Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 4 Jul 2026 19:20:51 +0900
Subject: [PATCH 08/18] freemjstudio/valid anagram

---
 valid-anagram/freemjstudio.py | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 valid-anagram/freemjstudio.py

diff --git a/valid-anagram/freemjstudio.py b/valid-anagram/freemjstudio.py
new file mode 100644
index 0000000000..ff422e7ebc
--- /dev/null
+++ b/valid-anagram/freemjstudio.py
@@ -0,0 +1,3 @@
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        return sorted(list(s)) == sorted(list(t))

From 22f93657678b939ae627162c7b871d60b65343a4 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 4 Jul 2026 19:20:51 +0900
Subject: [PATCH 09/18] freemjstudio/valid anagram

---
 3sum/freemjstudio.py            | 2 +-
 climbing-stairs/freemjstudio.py | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/3sum/freemjstudio.py b/3sum/freemjstudio.py
index 546a726a1a..92a6a3f66f 100644
--- a/3sum/freemjstudio.py
+++ b/3sum/freemjstudio.py
@@ -26,4 +26,4 @@ def threeSum(self, nums: list[int]) -> list[list[int]]:
                     left += 1
                 else: 
                     right -= 1
-        return answer 
\ No newline at end of file
+        return answer
diff --git a/climbing-stairs/freemjstudio.py b/climbing-stairs/freemjstudio.py
index d0eb35cb40..4b2e390a90 100644
--- a/climbing-stairs/freemjstudio.py
+++ b/climbing-stairs/freemjstudio.py
@@ -15,4 +15,3 @@ def climbStairs(self, n: int) -> int:
         for i in range(3, n+1):
             dp[i] = dp[i-1] + dp[i-2]
         return dp[n]
-        
\ No newline at end of file

From dae40c719c9d988d0216ee1dab275577741be5d7 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 4 Jul 2026 19:32:11 +0900
Subject: [PATCH 10/18] =?UTF-8?q?freemjstudio/valid-anagram=20=EB=91=90?=
 =?UTF-8?q?=EB=B2=88=EC=A7=B8=20=ED=92=80=EC=9D=B4?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 valid-anagram/freemjstudio.py | 31 ++++++++++++++++++++++++++++++-
 1 file changed, 30 insertions(+), 1 deletion(-)

diff --git a/valid-anagram/freemjstudio.py b/valid-anagram/freemjstudio.py
index ff422e7ebc..44fa9a12ea 100644
--- a/valid-anagram/freemjstudio.py
+++ b/valid-anagram/freemjstudio.py
@@ -1,3 +1,32 @@
+"""
+첫번째 풀이 
+시간 복잡도 : O(n log n)
+"""
+
 class Solution:
     def isAnagram(self, s: str, t: str) -> bool:
-        return sorted(list(s)) == sorted(list(t))
+        return sorted(s) == sorted(t)
+
+"""
+두번째 풀이
+시간 복잡도 : O(n)
+"""
+
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        # 반례 : s = ab, t = a 
+        # 이 경우에는 t에 없는 b가 존재하므로 False를 반환해야 한다.
+        if len(s) != len(t):
+            return False 
+        counter = {}
+
+        for ch in s: 
+            counter[ch] = counter.get(ch, 0) + 1
+        
+        for ch in t: 
+            if ch not in counter:
+                return False 
+            counter[ch] -= 1
+            if counter[ch] < 0:
+                return False 
+        return True

From 067afdb08b21253b02c99ab701824058cad43005 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Tue, 7 Jul 2026 01:30:57 +0900
Subject: [PATCH 11/18] add: product-of-array-except-self

---
 product-of-array-except-self/freemjstudio.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
 create mode 100644 product-of-array-except-self/freemjstudio.py

diff --git a/product-of-array-except-self/freemjstudio.py b/product-of-array-except-self/freemjstudio.py
new file mode 100644
index 0000000000..5638e08576
--- /dev/null
+++ b/product-of-array-except-self/freemjstudio.py
@@ -0,0 +1,17 @@
+class Solution:
+    def productExceptSelf(self, nums: List[int]) -> List[int]:
+        answer = [1] * len(nums)
+        
+        # left -> right 
+        for i in range(1, len(nums)):
+            answer[i] = answer[i-1] * nums[i-1] # 왼쪽에 있는 것들을 곱하자 
+
+        # right -> left
+        right_product = 1
+        for i in range(len(nums)-1, -1, -1):
+            answer[i] = answer[i] * right_product
+            right_product = right_product * nums[i]
+        
+
+        return answer 
+        
\ No newline at end of file

From 54d8362d23f1c4434bc1527c3ee3ea2ba19cc644 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 11 Jul 2026 12:21:31 +0900
Subject: [PATCH 12/18] freemjstudio/valid-palindrome

---
 valid-palindrome/freemjstudio.py | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 valid-palindrome/freemjstudio.py

diff --git a/valid-palindrome/freemjstudio.py b/valid-palindrome/freemjstudio.py
new file mode 100644
index 0000000000..f0d2c1c269
--- /dev/null
+++ b/valid-palindrome/freemjstudio.py
@@ -0,0 +1,21 @@
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        characters = "abcdefghijklmnopqrstuvwxyz0123456789"
+        s = s.lower()
+ 
+        filtered = ""
+        for ch in s: 
+            if ch in characters:
+                filtered += ch 
+  
+        n = len(filtered)
+        left = 0
+        right = n-1
+        while left <= n//2 and right >= n//2:
+            if filtered[left] == filtered[right]:
+                left += 1
+                right -= 1
+            else: 
+                return False
+        
+        return True
\ No newline at end of file

From def540d5f5de34584d661a3e1811821ce4f9fd66 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 11 Jul 2026 12:52:46 +0900
Subject: [PATCH 13/18] freemjstudio/number-of-1-bits

---
 number-of-1-bits/freemjstudio.py | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 number-of-1-bits/freemjstudio.py

diff --git a/number-of-1-bits/freemjstudio.py b/number-of-1-bits/freemjstudio.py
new file mode 100644
index 0000000000..e2821129fa
--- /dev/null
+++ b/number-of-1-bits/freemjstudio.py
@@ -0,0 +1,4 @@
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        binary = bin(n)
+        return binary.count("1")

From b33b7b1f7479ddc758bea25091f578fe6c540fd4 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 11 Jul 2026 12:54:17 +0900
Subject: [PATCH 14/18] freemjstudio/number-of-1-bits second solution

---
 number-of-1-bits/freemjstudio.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/number-of-1-bits/freemjstudio.py b/number-of-1-bits/freemjstudio.py
index e2821129fa..15d44ad981 100644
--- a/number-of-1-bits/freemjstudio.py
+++ b/number-of-1-bits/freemjstudio.py
@@ -2,3 +2,13 @@ class Solution:
     def hammingWeight(self, n: int) -> int:
         binary = bin(n)
         return binary.count("1")
+
+class Solution:
+    def hammingWeight(self, n: int) -> int:
+        count = 0 
+
+        while n > 0:
+            count += n % 2
+            n //=2
+        
+        return count
\ No newline at end of file

From fe69c94f926e3044db8c882eac1227f5fd21e8df Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 11 Jul 2026 16:50:44 +0900
Subject: [PATCH 15/18] freemjstudio/combination-sum

---
 combination-sum/freemjstudio.py  | 23 +++++++++++++++++++++++
 number-of-1-bits/freemjstudio.py |  1 +
 2 files changed, 24 insertions(+)
 create mode 100644 combination-sum/freemjstudio.py

diff --git a/combination-sum/freemjstudio.py b/combination-sum/freemjstudio.py
new file mode 100644
index 0000000000..459cb6fbfb
--- /dev/null
+++ b/combination-sum/freemjstudio.py
@@ -0,0 +1,23 @@
+class Solution:
+    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
+        answer = []
+        
+        def backtracking(start_idx, total, path): 
+            if target == total: 
+                answer.append(path[:]) # 새로운 리스트 객체를 만들어서 저장함.
+                # 리스트가 mutable 객체이므로 path[:] 로 복사하지 않으면 path 가 바뀔 때 answer 안의 값도 바뀌게 된다.
+                return 
+
+            if target < total:
+                return     
+
+            for idx in range(start_idx, len(candidates)): 
+                new_node = candidates[idx] # 동일한 숫자 재사용 가능함. start_idx 도 포함한다. 
+                path.append(new_node)
+
+                backtracking(idx, total + new_node, path) 
+                # 선택 취소 
+                path.pop()
+
+        backtracking(0, 0, [])
+        return answer 
\ No newline at end of file
diff --git a/number-of-1-bits/freemjstudio.py b/number-of-1-bits/freemjstudio.py
index 15d44ad981..de7fd5dd3a 100644
--- a/number-of-1-bits/freemjstudio.py
+++ b/number-of-1-bits/freemjstudio.py
@@ -3,6 +3,7 @@ def hammingWeight(self, n: int) -> int:
         binary = bin(n)
         return binary.count("1")
 
+# bin() 을 못쓰는 경우의 풀이
 class Solution:
     def hammingWeight(self, n: int) -> int:
         count = 0 

From d9759bcacce838ac652d6a9885ffce24f9660ba0 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 11 Jul 2026 16:52:27 +0900
Subject: [PATCH 16/18] Fix trailing whitespace in solutions

---
 3sum/freemjstudio.py                         | 12 ++++++------
 climbing-stairs/freemjstudio.py              |  4 ++--
 combination-sum/freemjstudio.py              | 20 ++++++++++----------
 contains-duplicate/freemjstudio.py           |  2 +-
 number-of-1-bits/freemjstudio.py             |  4 ++--
 product-of-array-except-self/freemjstudio.py | 11 +++++------
 top-k-frequent-elements/freemjstudio.py      | 18 +++++++++---------
 two-sum/freemjstudio.py                      |  6 +++---
 valid-anagram/freemjstudio.py                | 16 ++++++++--------
 valid-palindrome/freemjstudio.py             | 12 ++++++------
 10 files changed, 52 insertions(+), 53 deletions(-)

diff --git a/3sum/freemjstudio.py b/3sum/freemjstudio.py
index 92a6a3f66f..b6d16520c8 100644
--- a/3sum/freemjstudio.py
+++ b/3sum/freemjstudio.py
@@ -1,16 +1,16 @@
 class Solution:
     def threeSum(self, nums: list[int]) -> list[list[int]]:
         answer = []
-        nums.sort() 
-    
+        nums.sort()
+
         for i in range(len(nums)):
             # 중복된 원소가 있는 경우 똑같이 검사할 필요가 없으므로 건너뛴다.
             if i > 0 and nums[i] == nums[i-1]:
-                continue 
+                continue
 
             left, right = i+1, len(nums) - 1
 
-            while left < right: 
+            while left < right:
                 total = nums[i] + nums[left] + nums[right]
                 if total == 0:
                     answer.append([nums[i], nums[left], nums[right]])
@@ -18,12 +18,12 @@ def threeSum(self, nums: list[int]) -> list[list[int]]:
                     left += 1
                     right -= 1
 
-                    # 중복된 원소가 있는 경우 같은 정답 조합을 방지한다 
+                    # 중복된 원소가 있는 경우 같은 정답 조합을 방지한다
                     while left < right and nums[left] == nums[left -1]:
                         left += 1
 
                 elif total < 0:
                     left += 1
-                else: 
+                else:
                     right -= 1
         return answer
diff --git a/climbing-stairs/freemjstudio.py b/climbing-stairs/freemjstudio.py
index 4b2e390a90..29bc2fa9a3 100644
--- a/climbing-stairs/freemjstudio.py
+++ b/climbing-stairs/freemjstudio.py
@@ -1,12 +1,12 @@
 class Solution:
     def climbStairs(self, n: int) -> int:
-        answer = 0 
+        answer = 0
         if n == 1: # ways(1) = 1
             return 1
 
         if n == 2: # ways(2) = 2
             return 2
-        
+
         dp = [0] * 46 # 1 <= n <= 45
         dp[1] = 1
         dp[2] = 2
diff --git a/combination-sum/freemjstudio.py b/combination-sum/freemjstudio.py
index 459cb6fbfb..3dc8bdc42f 100644
--- a/combination-sum/freemjstudio.py
+++ b/combination-sum/freemjstudio.py
@@ -1,23 +1,23 @@
 class Solution:
     def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
         answer = []
-        
-        def backtracking(start_idx, total, path): 
-            if target == total: 
+
+        def backtracking(start_idx, total, path):
+            if target == total:
                 answer.append(path[:]) # 새로운 리스트 객체를 만들어서 저장함.
                 # 리스트가 mutable 객체이므로 path[:] 로 복사하지 않으면 path 가 바뀔 때 answer 안의 값도 바뀌게 된다.
-                return 
+                return
 
             if target < total:
-                return     
+                return
 
-            for idx in range(start_idx, len(candidates)): 
-                new_node = candidates[idx] # 동일한 숫자 재사용 가능함. start_idx 도 포함한다. 
+            for idx in range(start_idx, len(candidates)):
+                new_node = candidates[idx] # 동일한 숫자 재사용 가능함. start_idx 도 포함한다.
                 path.append(new_node)
 
-                backtracking(idx, total + new_node, path) 
-                # 선택 취소 
+                backtracking(idx, total + new_node, path)
+                # 선택 취소
                 path.pop()
 
         backtracking(0, 0, [])
-        return answer 
\ No newline at end of file
+        return answer
\ No newline at end of file
diff --git a/contains-duplicate/freemjstudio.py b/contains-duplicate/freemjstudio.py
index 6048a3c5ea..b9cdeddb4c 100644
--- a/contains-duplicate/freemjstudio.py
+++ b/contains-duplicate/freemjstudio.py
@@ -1,6 +1,6 @@
 class Solution:
     def containsDuplicate(self, nums: List[int]) -> bool:
-        first = len(nums) # O(1) : 리스트 객체는 이미 자기자신의 길이를 저장하고 있음 
+        first = len(nums) # O(1) : 리스트 객체는 이미 자기자신의 길이를 저장하고 있음
         set_nums = set(nums) # O(N)
         second = len(set_nums)
         return (first != second)
diff --git a/number-of-1-bits/freemjstudio.py b/number-of-1-bits/freemjstudio.py
index de7fd5dd3a..9e657f790d 100644
--- a/number-of-1-bits/freemjstudio.py
+++ b/number-of-1-bits/freemjstudio.py
@@ -6,10 +6,10 @@ def hammingWeight(self, n: int) -> int:
 # bin() 을 못쓰는 경우의 풀이
 class Solution:
     def hammingWeight(self, n: int) -> int:
-        count = 0 
+        count = 0
 
         while n > 0:
             count += n % 2
             n //=2
-        
+
         return count
\ No newline at end of file
diff --git a/product-of-array-except-self/freemjstudio.py b/product-of-array-except-self/freemjstudio.py
index 5638e08576..09df575b56 100644
--- a/product-of-array-except-self/freemjstudio.py
+++ b/product-of-array-except-self/freemjstudio.py
@@ -1,17 +1,16 @@
 class Solution:
     def productExceptSelf(self, nums: List[int]) -> List[int]:
         answer = [1] * len(nums)
-        
-        # left -> right 
+
+        # left -> right
         for i in range(1, len(nums)):
-            answer[i] = answer[i-1] * nums[i-1] # 왼쪽에 있는 것들을 곱하자 
+            answer[i] = answer[i-1] * nums[i-1] # 왼쪽에 있는 것들을 곱하자
 
         # right -> left
         right_product = 1
         for i in range(len(nums)-1, -1, -1):
             answer[i] = answer[i] * right_product
             right_product = right_product * nums[i]
-        
 
-        return answer 
-        
\ No newline at end of file
+
+        return answer
diff --git a/top-k-frequent-elements/freemjstudio.py b/top-k-frequent-elements/freemjstudio.py
index 184c87aeee..ed8cf1c339 100644
--- a/top-k-frequent-elements/freemjstudio.py
+++ b/top-k-frequent-elements/freemjstudio.py
@@ -5,18 +5,18 @@ def topKFrequent(self, nums: List[int], k: int) -> List[int]:
         answer = []
         count = dict()
         heap = []
-        if len(nums) <= 1: 
+        if len(nums) <= 1:
             return nums
-        # O(N)    
-        for num in nums: 
+        # O(N)
+        for num in nums:
             count[num] = count.get(num, 0) + 1
-        
-        # heap 의 크기는 최대 k 로 제한함. 
+
+        # heap 의 크기는 최대 k 로 제한함.
         # unique 한 M개의 숫자를 선형 순회 O(M)
         for num, freq in count.items():
-            if len(heap) < k: 
+            if len(heap) < k:
                 heapq.heappush(heap, (freq, num))         # O(logK)
-            else: 
+            else:
                 if heap[0][0] < freq:
                     heapq.heappop(heap)         # O(logK)
                     heapq.heappush(heap, (freq, num))         # O(logK)
@@ -25,5 +25,5 @@ def topKFrequent(self, nums: List[int], k: int) -> List[int]:
             k, v = heapq.heappop(heap)
             answer.append(v)
 
-        return answer 
-        
+        return answer
+
diff --git a/two-sum/freemjstudio.py b/two-sum/freemjstudio.py
index a274028f5c..69426fb065 100644
--- a/two-sum/freemjstudio.py
+++ b/two-sum/freemjstudio.py
@@ -5,8 +5,8 @@ def twoSum(self, nums: List[int], target: int) -> List[int]:
         for i in range(len(nums)):
             current_num = nums[i]
             diff = target - current_num
-            if diff in hashmap.keys(): 
-                return [i, hashmap[diff]] 
+            if diff in hashmap.keys():
+                return [i, hashmap[diff]]
             hashmap[current_num] = i # store the index of current num
-        
+
         return answer
diff --git a/valid-anagram/freemjstudio.py b/valid-anagram/freemjstudio.py
index 44fa9a12ea..43da0864a5 100644
--- a/valid-anagram/freemjstudio.py
+++ b/valid-anagram/freemjstudio.py
@@ -1,5 +1,5 @@
 """
-첫번째 풀이 
+첫번째 풀이
 시간 복잡도 : O(n log n)
 """
 
@@ -14,19 +14,19 @@ def isAnagram(self, s: str, t: str) -> bool:
 
 class Solution:
     def isAnagram(self, s: str, t: str) -> bool:
-        # 반례 : s = ab, t = a 
+        # 반례 : s = ab, t = a
         # 이 경우에는 t에 없는 b가 존재하므로 False를 반환해야 한다.
         if len(s) != len(t):
-            return False 
+            return False
         counter = {}
 
-        for ch in s: 
+        for ch in s:
             counter[ch] = counter.get(ch, 0) + 1
-        
-        for ch in t: 
+
+        for ch in t:
             if ch not in counter:
-                return False 
+                return False
             counter[ch] -= 1
             if counter[ch] < 0:
-                return False 
+                return False
         return True
diff --git a/valid-palindrome/freemjstudio.py b/valid-palindrome/freemjstudio.py
index f0d2c1c269..3c7d319cca 100644
--- a/valid-palindrome/freemjstudio.py
+++ b/valid-palindrome/freemjstudio.py
@@ -2,12 +2,12 @@ class Solution:
     def isPalindrome(self, s: str) -> bool:
         characters = "abcdefghijklmnopqrstuvwxyz0123456789"
         s = s.lower()
- 
+
         filtered = ""
-        for ch in s: 
+        for ch in s:
             if ch in characters:
-                filtered += ch 
-  
+                filtered += ch
+
         n = len(filtered)
         left = 0
         right = n-1
@@ -15,7 +15,7 @@ def isPalindrome(self, s: str) -> bool:
             if filtered[left] == filtered[right]:
                 left += 1
                 right -= 1
-            else: 
+            else:
                 return False
-        
+
         return True
\ No newline at end of file

From c4b38167d946f6fe75ae25f233c886601249819c Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 11 Jul 2026 16:54:06 +0900
Subject: [PATCH 17/18] Remove trailing blank line

---
 top-k-frequent-elements/freemjstudio.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/top-k-frequent-elements/freemjstudio.py b/top-k-frequent-elements/freemjstudio.py
index ed8cf1c339..ca5228336a 100644
--- a/top-k-frequent-elements/freemjstudio.py
+++ b/top-k-frequent-elements/freemjstudio.py
@@ -26,4 +26,3 @@ def topKFrequent(self, nums: List[int], k: int) -> List[int]:
             answer.append(v)
 
         return answer
-

From 1e6b42ac6af29e76b72397d97b2f74ab17c36ba1 Mon Sep 17 00:00:00 2001
From: freemjstudio <mjwoo0@naver.com>
Date: Sat, 11 Jul 2026 16:57:43 +0900
Subject: [PATCH 18/18] Fix missing final newlines

---
 combination-sum/freemjstudio.py  | 2 +-
 number-of-1-bits/freemjstudio.py | 2 +-
 valid-palindrome/freemjstudio.py | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/combination-sum/freemjstudio.py b/combination-sum/freemjstudio.py
index 3dc8bdc42f..d6824f6949 100644
--- a/combination-sum/freemjstudio.py
+++ b/combination-sum/freemjstudio.py
@@ -20,4 +20,4 @@ def backtracking(start_idx, total, path):
                 path.pop()
 
         backtracking(0, 0, [])
-        return answer
\ No newline at end of file
+        return answer
diff --git a/number-of-1-bits/freemjstudio.py b/number-of-1-bits/freemjstudio.py
index 9e657f790d..ef95ab1dea 100644
--- a/number-of-1-bits/freemjstudio.py
+++ b/number-of-1-bits/freemjstudio.py
@@ -12,4 +12,4 @@ def hammingWeight(self, n: int) -> int:
             count += n % 2
             n //=2
 
-        return count
\ No newline at end of file
+        return count
diff --git a/valid-palindrome/freemjstudio.py b/valid-palindrome/freemjstudio.py
index 3c7d319cca..cb93b4e4e9 100644
--- a/valid-palindrome/freemjstudio.py
+++ b/valid-palindrome/freemjstudio.py
@@ -18,4 +18,4 @@ def isPalindrome(self, s: str) -> bool:
             else:
                 return False
 
-        return True
\ No newline at end of file
+        return True