From 19d7689457aa42e59959800ebf516ec62e4380c8 Mon Sep 17 00:00:00 2001
From: 1lsang <ilsangpark.98@gmail.com>
Date: Sat, 15 Nov 2025 11:31:07 +0900
Subject: [PATCH 1/4] solve contains-duplicate

---
 contains-duplicate/1lsang.ts | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 contains-duplicate/1lsang.ts

diff --git a/contains-duplicate/1lsang.ts b/contains-duplicate/1lsang.ts
new file mode 100644
index 0000000000..130ca89fed
--- /dev/null
+++ b/contains-duplicate/1lsang.ts
@@ -0,0 +1,5 @@
+function containsDuplicate(nums: number[]): boolean {
+    // Javascript의 Set은 내부적으로 해시테이블을 이용해서, O(n)으로 중복 제거
+    const uniqueNums = Array.from(new Set(nums).values());
+    return uniqueNums.length !== nums.length;
+};

From ffc71a6414925cdee0bb80e636986f31b2ecc316 Mon Sep 17 00:00:00 2001
From: 1lsang <ilsangpark.98@gmail.com>
Date: Sat, 15 Nov 2025 13:27:54 +0900
Subject: [PATCH 2/4] solve two-sum

---
 two-sum/1lsang.ts | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 two-sum/1lsang.ts

diff --git a/two-sum/1lsang.ts b/two-sum/1lsang.ts
new file mode 100644
index 0000000000..3dd959bdfd
--- /dev/null
+++ b/two-sum/1lsang.ts
@@ -0,0 +1,28 @@
+// 1. 가장 간단한 방법 이중 for문 (Runtime: 175ms / Memory: 55.8MB)
+// function twoSum(nums: number[], target: number): number[] {
+//     const length = nums.length;
+//     for (let i = 0; i < length; i++) {
+//         for (let j = 0; j < length; j++) {
+//             if (i === j) continue;
+//             if (nums[i] + nums[j] === target) return [i, j]
+//         }
+//     }
+//     return [];
+// };
+
+// 2. 시간 복잡도 개선 (Runtime: 9ms / Memory: 60.4MB)
+function twoSum(nums: number[], target: number): number[] {
+    const numObj = {};
+    nums.forEach((num, index) => {numObj[num] ? numObj[num].push(index) : numObj[num]=[index]});
+    for (let i = 0; i<nums.length; i++) {
+        const num = target - nums[i];
+        if (numObj[num]?.length === 1) {
+            if (i === numObj[num][0]) continue;
+            return [i, numObj[num][0]];
+        }
+        else if (numObj[num]?.length === 2) {
+            return numObj[num];
+        }
+    }
+    return [];
+};

From 09fa9e9ec742cfb021528295d209372285d906a6 Mon Sep 17 00:00:00 2001
From: 1lsang <ilsangpark.98@gmail.com>
Date: Sat, 15 Nov 2025 14:16:09 +0900
Subject: [PATCH 3/4] solve top-k-frequent-elements

---
 top-k-frequent-elements/1lsang.ts | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 top-k-frequent-elements/1lsang.ts

diff --git a/top-k-frequent-elements/1lsang.ts b/top-k-frequent-elements/1lsang.ts
new file mode 100644
index 0000000000..47a347f17d
--- /dev/null
+++ b/top-k-frequent-elements/1lsang.ts
@@ -0,0 +1,15 @@
+// Runtime: 9ms / Memory: 60MB
+function topKFrequent(nums: number[], k: number): number[] {
+    const numFrequency:Record<number, number> = {}; // { n: freq }
+
+    for (let i=0; i<nums.length; i++) {
+        const n = nums[i];
+        if (numFrequency[n]) numFrequency[n] = numFrequency[n] + 1;
+        else numFrequency[n] = 1;
+    }
+
+    return Object.entries(numFrequency)
+        .sort((a, b) => b[1] - a[1])
+        .slice(0, k)
+        .map(([_, n])=> n);
+};
\ No newline at end of file

From 0e8f690ec35216b3ec954b852310adfa5766ea2e Mon Sep 17 00:00:00 2001
From: 1lsang <ilsangpark.98@gmail.com>
Date: Sat, 15 Nov 2025 14:22:18 +0900
Subject: [PATCH 4/4] add line breaks at the end of files

---
 top-k-frequent-elements/1lsang.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/top-k-frequent-elements/1lsang.ts b/top-k-frequent-elements/1lsang.ts
index 47a347f17d..2887f3abf1 100644
--- a/top-k-frequent-elements/1lsang.ts
+++ b/top-k-frequent-elements/1lsang.ts
@@ -12,4 +12,4 @@ function topKFrequent(nums: number[], k: number): number[] {
         .sort((a, b) => b[1] - a[1])
         .slice(0, k)
         .map(([_, n])=> n);
-};
\ No newline at end of file
+};