From b6e35e7b3443d60e415e1f8725dc12e6f45986e6 Mon Sep 17 00:00:00 2001
From: Hyun Chan Park <126567839+Chanz82@users.noreply.github.com>
Date: Fri, 26 Jun 2026 01:17:37 +0100
Subject: [PATCH 1/4] Implement containsDuplicate method in Solution class

---
 contains-duplicate/Chanz82.py | 10 ++++++++++
 1 file changed, 10 insertions(+)
 create mode 100644 contains-duplicate/Chanz82.py

diff --git a/contains-duplicate/Chanz82.py b/contains-duplicate/Chanz82.py
new file mode 100644
index 0000000000..55fcc66236
--- /dev/null
+++ b/contains-duplicate/Chanz82.py
@@ -0,0 +1,10 @@
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        hashmap = dict()
+        sorted(nums)
+        for num in nums:
+            if hashmap.get(num, False) == True: 
+                return True
+            else :
+                hashmap[num] = True
+        return False

From e026ddde21f265c9f0363031e4a15bb5cb22c41f Mon Sep 17 00:00:00 2001
From: Hyun Chan Park <126567839+Chanz82@users.noreply.github.com>
Date: Fri, 26 Jun 2026 23:29:01 +0100
Subject: [PATCH 2/4] Add twoSum method in Solution class

Implement twoSum method to find indices of two numbers that add up to target.
---
 two-sum/Chanz.py | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 two-sum/Chanz.py

diff --git a/two-sum/Chanz.py b/two-sum/Chanz.py
new file mode 100644
index 0000000000..5c41451095
--- /dev/null
+++ b/two-sum/Chanz.py
@@ -0,0 +1,20 @@
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+
+        ## 공간 복잡도 : O(n)
+        ## - n 개수 만큼의 hashmap 공간만을 사용하므로 공간복잡도가 O(n)이라고 생각합니다.
+
+        ## 시간 복잡도 : O(n)
+        ## - hashmap에 값과 idx를 매칭하는 작업을 n번 수행합니다.
+        ## - 이후 다시 nums를 순회하면서 target이 되는 짝을 찾습니다.
+        ## - 따라서 Worst N번 이므로, 2n = O(n)이라고 생각합니다.
+
+        hashmap = dict()
+        for idx, num in enumerate(nums):
+            hashmap[num] = idx
+        
+        for idx, num in enumerate(nums):
+            matched_num_idx = hashmap.get(target-num)
+            if matched_num_idx and matched_num_idx != idx:
+                return [idx, matched_num_idx]
+        

From e8339c9b9f962f89ab0459ec6ebdefd96a474e2b Mon Sep 17 00:00:00 2001
From: Hyun Chan Park <126567839+Chanz82@users.noreply.github.com>
Date: Fri, 26 Jun 2026 23:30:47 +0100
Subject: [PATCH 3/4] Rename Chanz.py to Chanz82.py

---
 two-sum/{Chanz.py => Chanz82.py} | 0
 1 file changed, 0 insertions(+), 0 deletions(-)
 rename two-sum/{Chanz.py => Chanz82.py} (100%)

diff --git a/two-sum/Chanz.py b/two-sum/Chanz82.py
similarity index 100%
rename from two-sum/Chanz.py
rename to two-sum/Chanz82.py

From 40cb681a27a3b615df351f65a89f2f2e0c58840e Mon Sep 17 00:00:00 2001
From: Hyun Chan Park <126567839+Chanz82@users.noreply.github.com>
Date: Fri, 26 Jun 2026 23:46:22 +0100
Subject: [PATCH 4/4] Optimize two-sum algorithm with single loop

Refactor two-sum solution to use a single loop for finding matches.
---
 two-sum/Chanz82.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/two-sum/Chanz82.py b/two-sum/Chanz82.py
index 5c41451095..55ef11f80e 100644
--- a/two-sum/Chanz82.py
+++ b/two-sum/Chanz82.py
@@ -10,11 +10,11 @@ def twoSum(self, nums: List[int], target: int) -> List[int]:
         ## - 따라서 Worst N번 이므로, 2n = O(n)이라고 생각합니다.
 
         hashmap = dict()
+
         for idx, num in enumerate(nums):
-            hashmap[num] = idx
-        
-        for idx, num in enumerate(nums):
-            matched_num_idx = hashmap.get(target-num)
-            if matched_num_idx and matched_num_idx != idx:
-                return [idx, matched_num_idx]
+            possible_match = target - num
+            if possible_match in hashmap:
+                return [idx, hashmap[possible_match]]
+            else:
+                hashmap[num] = idx