From 865ed8deb5198d5f8c8038db9754dfc4d5ae77f9 Mon Sep 17 00:00:00 2001 From: freemjstudio Date: Mon, 22 Jun 2026 01:07:05 +0900 Subject: [PATCH 01/10] 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 Date: Sat, 27 Jun 2026 16:38:18 +0900 Subject: [PATCH 02/10] 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 Date: Sat, 27 Jun 2026 16:38:42 +0900 Subject: [PATCH 03/10] 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 Date: Sun, 28 Jun 2026 15:38:37 +0900 Subject: [PATCH 04/10] 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 Date: Thu, 2 Jul 2026 00:42:35 +0900 Subject: [PATCH 05/10] =?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 Date: Sat, 4 Jul 2026 13:36:49 +0900 Subject: [PATCH 06/10] 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 Date: Sat, 4 Jul 2026 16:28:00 +0900 Subject: [PATCH 07/10] 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 Date: Sat, 4 Jul 2026 19:20:51 +0900 Subject: [PATCH 08/10] 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 Date: Sat, 4 Jul 2026 19:20:51 +0900 Subject: [PATCH 09/10] 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 Date: Sat, 4 Jul 2026 19:32:11 +0900 Subject: [PATCH 10/10] =?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