From f16cc2c982a09c4d86a61a961742d2ddad83458c Mon Sep 17 00:00:00 2001
From: anniemon <seojung19@gmail.com>
Date: Sat, 4 Jan 2025 03:35:03 +0900
Subject: [PATCH 1/3] feat: merge two sorted lists

---
 merge-two-sorted-lists/anniemon.js | 39 ++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 merge-two-sorted-lists/anniemon.js

diff --git a/merge-two-sorted-lists/anniemon.js b/merge-two-sorted-lists/anniemon.js
new file mode 100644
index 000000000..38aacc8fe
--- /dev/null
+++ b/merge-two-sorted-lists/anniemon.js
@@ -0,0 +1,39 @@
+/**
+ * 시간 복잡도:
+ *   list1의 길이가 m, list2의 길이가 n이면
+ *   포인터가 최대 m + n만큼 순회하므로 O(m + n)
+ * 공간 복잡도:
+ *   포인터를 사용하므로 O(1)
+ */
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} list1
+ * @param {ListNode} list2
+ * @return {ListNode}
+ */
+var mergeTwoLists = function(list1, list2) {
+  const head = new ListNode(0, null);
+  let pointer = head;
+  while(list1 && list2) {
+      if(list1.val < list2.val) {
+          pointer.next = list1;
+          list1 = list1.next;
+      } else {
+          pointer.next = list2;
+          list2 = list2.next;
+      }
+      pointer = pointer.next;
+  }
+  if(list1) {
+      pointer.next = list1;
+  } else {
+      pointer.next = list2;
+  }
+  return head.next;
+};

From 4bc2ed946ed86fbe06dd9b15c7091da3b4202b51 Mon Sep 17 00:00:00 2001
From: anniemon <seojung19@gmail.com>
Date: Sat, 4 Jan 2025 03:35:11 +0900
Subject: [PATCH 2/3] feat: missing number

---
 missing-number/anniemon.js | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 missing-number/anniemon.js

diff --git a/missing-number/anniemon.js b/missing-number/anniemon.js
new file mode 100644
index 000000000..f38f1323f
--- /dev/null
+++ b/missing-number/anniemon.js
@@ -0,0 +1,19 @@
+/**
+ * 시간 복잡도: nums.length + 1만큼 순회하므로 O(n)
+ * 공간 복잡도: totalSum, numsSum 변수를 사용하므로 O(1)
+ */
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var missingNumber = function(nums) {
+  let totalSum = 0;
+  for(let i = 0; i <= nums.length; i++) {
+      totalSum += i;
+  }
+  let numsSum = 0;
+  for(const n of nums) {
+      numsSum += n;
+  }
+  return totalSum - numsSum;
+};

From 50b69f5e9be2d3011affb0cfdf10d397966d5a79 Mon Sep 17 00:00:00 2001
From: Seojung Noh <73627443+anniemon@users.noreply.github.com>
Date: Sat, 4 Jan 2025 10:04:07 +0900
Subject: [PATCH 3/3] refactor: solve mathematically

Co-authored-by: Dongyeong Chon <dngyng1000@gmail.com>
---
 missing-number/anniemon.js | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/missing-number/anniemon.js b/missing-number/anniemon.js
index f38f1323f..5700e6746 100644
--- a/missing-number/anniemon.js
+++ b/missing-number/anniemon.js
@@ -7,10 +7,8 @@
  * @return {number}
  */
 var missingNumber = function(nums) {
-  let totalSum = 0;
-  for(let i = 0; i <= nums.length; i++) {
-      totalSum += i;
-  }
+  const n = nums.length;
+  const totalSum = n * (n + 1) / 2;
   let numsSum = 0;
   for(const n of nums) {
       numsSum += n;