From 4eb4431dc7975409de995cf2a32da56ba7540c27 Mon Sep 17 00:00:00 2001
From: Nayeon <nayeonkn0330@gmail.com>
Date: Mon, 16 Dec 2024 12:11:56 +0900
Subject: [PATCH 1/6] Create KwonNayeon.py
---
valid-anagram/KwonNayeon.py | 1 +
1 file changed, 1 insertion(+)
create mode 100644 valid-anagram/KwonNayeon.py
diff --git a/valid-anagram/KwonNayeon.py b/valid-anagram/KwonNayeon.py
new file mode 100644
index 000000000..8b1378917
--- /dev/null
+++ b/valid-anagram/KwonNayeon.py
@@ -0,0 +1 @@
+
From 9a78a481b42dd4f2c232c59a0b8bc02d993c96bf Mon Sep 17 00:00:00 2001
From: Nayeon <nayeonkn0330@gmail.com>
Date: Mon, 16 Dec 2024 12:13:19 +0900
Subject: [PATCH 2/6] Add placeholder file for 'Valid Anagram' problem
---
valid-anagram/KwonNayeon.py | 1 +
1 file changed, 1 insertion(+)
diff --git a/valid-anagram/KwonNayeon.py b/valid-anagram/KwonNayeon.py
index 8b1378917..139597f9c 100644
--- a/valid-anagram/KwonNayeon.py
+++ b/valid-anagram/KwonNayeon.py
@@ -1 +1,2 @@
+
From a636a6764c6041a13e130a8d2814f8ee0047e9bf Mon Sep 17 00:00:00 2001
From: Nayeon <nayeonkn0330@gmail.com>
Date: Mon, 16 Dec 2024 14:24:40 +0900
Subject: [PATCH 3/6] Solved 218. Valid Anagram using Python code
---
valid-anagram/KwonNayeon.py | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/valid-anagram/KwonNayeon.py b/valid-anagram/KwonNayeon.py
index 139597f9c..f5a78c0c5 100644
--- a/valid-anagram/KwonNayeon.py
+++ b/valid-anagram/KwonNayeon.py
@@ -1,2 +1,21 @@
+"""
+Constraints:
+ - 1 <= len(s), len(t) <= 50_000
+ - s and t consist of lowercase English letters (a-z) only
+Time Complexity:
+ - O(n log n)
+Space Complexity:
+ - O(n)
+"""
+class Solution:
+ def isAnagram(self, s: str, t: str) -> bool:
+
+ s = s.replace(' ', '').lower()
+ t = t.replace(' ', '').lower()
+
+ if sorted(s) == sorted(t):
+ return True
+ else:
+ return False
From 18e7dfab8b4ddf8adf8c1d46a1993b445fb52db7 Mon Sep 17 00:00:00 2001
From: Nayeon <nayeonkn0330@gmail.com>
Date: Mon, 16 Dec 2024 16:36:04 +0900
Subject: [PATCH 4/6] Solved 230. Climbing Stairs using Python code
---
climbing-stairs/KwonNayeon.py | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
create mode 100644 climbing-stairs/KwonNayeon.py
diff --git a/climbing-stairs/KwonNayeon.py b/climbing-stairs/KwonNayeon.py
new file mode 100644
index 000000000..054c8df0b
--- /dev/null
+++ b/climbing-stairs/KwonNayeon.py
@@ -0,0 +1,23 @@
+"""
+Constraints:
+ - 1 <= n <= 45
+
+Time Complexity:
+ - O(n)
+Space Complexity:
+ - O(n)
+"""
+
+class Solution:
+ def climbStairs(self, n: int) -> int:
+ if n == 1:
+ return 1
+ if n == 2:
+ return 2
+
+ dp = [0] * (n+1)
+ dp[1], dp[2] = 1, 2
+
+ for i in range(3, n+1):
+ dp[i] = dp[i-1] + dp[i-2]
+ return dp[n]
From 0e4d1ef5c1fe56cee150abe78c8fed5a58dcda87 Mon Sep 17 00:00:00 2001
From: Nayeon <nayeonkn0330@gmail.com>
Date: Tue, 17 Dec 2024 19:32:16 +0900
Subject: [PATCH 5/6] Solved 241. 3Sum using Python code
---
3sum/KwonNayeon.py | 42 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 42 insertions(+)
create mode 100644 3sum/KwonNayeon.py
diff --git a/3sum/KwonNayeon.py b/3sum/KwonNayeon.py
new file mode 100644
index 000000000..3e5852dfb
--- /dev/null
+++ b/3sum/KwonNayeon.py
@@ -0,0 +1,42 @@
+"""
+Constraints:
+1. 3 <= nums.length <= 3000
+2. -10^5 <= nums[i] <= 10^5
+
+Time Complexity:
+ - O(n^2) (정렬은 O(n log n), 이중 반복문은 O(n^2))
+Space Complexity:
+ - O(n) (결과 리스트)
+"""
+
+class Solution:
+ def threeSum(self, nums: List[int]) -> List[List[int]]:
+ nums.sort()
+ result = []
+
+ for i in range(len(nums) - 2):
+ if i > 0 and nums[i] == nums[i-1]:
+ continue
+
+ left, right = i+1, len(nums)-1
+
+ while left < right:
+ sum = nums[i] + nums[left] + nums[right]
+
+ if sum == 0:
+ result.append([nums[i], nums[left], nums[right]])
+
+ while left < right and nums[left] == nums[left+1]:
+ left += 1
+ while left < right and nums[right] == nums[right-1]:
+ right -= 1
+
+ left += 1
+ right -= 1
+
+ elif sum < 0:
+ left += 1
+ else:
+ right -= 1
+
+ return result
From 91937ec06e305391a0092d51ffc6f8a798a310ee Mon Sep 17 00:00:00 2001
From: Nayeon <nayeonkn0330@gmail.com>
Date: Thu, 19 Dec 2024 18:03:20 +0900
Subject: [PATCH 6/6] Solved 253. Construct Binary Tree From Preorder And
Inorder Traversal using Python code
---
.../KwonNayeon.py | 28 +++++++++++++++++++
1 file changed, 28 insertions(+)
create mode 100644 construct-binary-tree-from-preorder-and-inorder-traversal/KwonNayeon.py
diff --git a/construct-binary-tree-from-preorder-and-inorder-traversal/KwonNayeon.py b/construct-binary-tree-from-preorder-and-inorder-traversal/KwonNayeon.py
new file mode 100644
index 000000000..d158f34ea
--- /dev/null
+++ b/construct-binary-tree-from-preorder-and-inorder-traversal/KwonNayeon.py
@@ -0,0 +1,28 @@
+"""
+Constraints:
+ 1. 1 <= preorder.length <= 3000
+ 2. inorder.length == preorder.length
+ 3. -3000 <= preorder[i], inorder[i] <= 3000
+ 4. preorder and inorder consist of unique values
+ 5. Each value of inorder also appears in preorder
+ 6. preorder is guaranteed to be the preorder traversal of the tree
+ 7. inorder is guaranteed to be the inorder traversal of the tree
+
+Time Complexity:
+ - O(N^2). 각 노드(N)마다 inorder에서 index를 찾는 연산(N)이 필요하고, 각 노드를 한 번씩 방문하여 트리를 구성하기 때문.
+Space Complexity:
+ - O(N). 재귀 호출 스택을 위한 공간이 필요하며, 최악의 경우(한쪽으로 치우친 트리) 재귀 깊이가 N까지 갈 수 있기 때문.
+"""
+
+class Solution:
+ def buildTree(self, preorder: List[int], inorder: List[int]) -> Optional[TreeNode]:
+ if not preorder or not inorder:
+ return None
+
+ root = TreeNode(preorder[0])
+ mid = inorder.index(preorder[0])
+
+ root.left = self.buildTree(preorder[1:mid+1], inorder[:mid])
+ root.right = self.buildTree(preorder[mid+1:], inorder[mid+1:])
+
+ return root