From 2904515e1803d4d07d0a0d507bb1e8e81e7fb37c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EC=9E=A5=EC=9E=AC=EC=A0=95?=
 <jangjaejeong@baejieun-ui-MacBookPro.local>
Date: Sun, 16 Nov 2025 15:38:45 +0900
Subject: [PATCH 1/2] 3sum

---
 3sum/jaejeong1.java | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 3sum/jaejeong1.java

diff --git a/3sum/jaejeong1.java b/3sum/jaejeong1.java
new file mode 100644
index 0000000000..0f610905c5
--- /dev/null
+++ b/3sum/jaejeong1.java
@@ -0,0 +1,34 @@
+class Solution {
+    public List<List<Integer>> threeSum(int[] nums) {
+        // 전체 시간 복잡도: O(N2), 공간 복잡도: O(N)
+        // 정렬: 시간 복잡도: O(N log N)
+        Arrays.sort(nums);
+        List<List<Integer>> result = new ArrayList<>();
+        // x 하나 잡아놓고, 투포인터 사용해서 y + z 가 -x 보다 크면 z 를 - 1, 적으면 y 를 + 1, y와 z가 만나면 break, y + z 가 -x 와 같으면 정답
+        // 0 보다 큰 케이스는 돌 필요가 없음
+        for (int i = 0; i < nums.length && nums[i] <= 0; ++i) {
+            // 시간 복잡도: O(N)
+            if (i == 0 || nums[i - 1] != nums[i]) {
+                findThreeSum(nums, i, result);
+            }
+        }
+        return result;
+    }
+
+    void findThreeSum(int[] nums, int i, List<List<Integer>> result) {
+        // 시간 복잡도: O(N), 공간 복잡도: O(3N) = O(N)
+        int left = i + 1, right = nums.length - 1;
+        while (left < right) {
+            int sum = nums[i] + nums[left] + nums[right];
+            if (sum < 0) {
+                ++left;
+            } else if (sum > 0) {
+                --right;
+            } else {
+                // 정답 케이스 찾아서 결과에 넣기
+                result.add(Arrays.asList(nums[i], nums[left++], nums[right--]));
+                while (left < right && nums[left] == nums[left - 1]) ++left; // 숫자 중복인 케이스 넘어가기
+            }
+        }
+    }
+}
\ No newline at end of file

From bd09a9ef593adbe78e7e36f8788bb7338fe6865a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EC=9E=A5=EC=9E=AC=EC=A0=95?=
 <jangjaejeong@baejieun-ui-MacBookPro.local>
Date: Sun, 16 Nov 2025 15:42:06 +0900
Subject: [PATCH 2/2] =?UTF-8?q?=EA=B0=9C=ED=96=89?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 3sum/jaejeong1.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/3sum/jaejeong1.java b/3sum/jaejeong1.java
index 0f610905c5..f7b20b7f14 100644
--- a/3sum/jaejeong1.java
+++ b/3sum/jaejeong1.java
@@ -31,4 +31,4 @@ void findThreeSum(int[] nums, int i, List<List<Integer>> result) {
             }
         }
     }
-}
\ No newline at end of file
+}