From 6ddb81837e92d973a69efbdc4f9f4f97de3ad232 Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Mon, 2 Jun 2025 02:45:41 -0700
Subject: [PATCH 1/6] invert binary tree solution

---
 invert-binary-tree/byol-han.js | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 invert-binary-tree/byol-han.js

diff --git a/invert-binary-tree/byol-han.js b/invert-binary-tree/byol-han.js
new file mode 100644
index 000000000..2775f8a0e
--- /dev/null
+++ b/invert-binary-tree/byol-han.js
@@ -0,0 +1,21 @@
+/**
+ * https://leetcode.com/problems/invert-binary-tree/submissions/1651537941/
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {TreeNode}
+ */
+var invertTree = function (root) {
+  if (root === null) return null;
+
+  // 왼쪽과 오른쪽 자식 노드 바꾸기
+  [root.left, root.right] = [invertTree(root.right), invertTree(root.left)];
+
+  return root;
+};

From d20e519fc35a3d4911e4ffc55889a2b545096e95 Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sat, 7 Jun 2025 02:09:52 -0700
Subject: [PATCH 2/6] search-in-rotated-sorted-array solution

---
 search-in-rotated-sorted-array/byol-han.js | 46 ++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 search-in-rotated-sorted-array/byol-han.js

diff --git a/search-in-rotated-sorted-array/byol-han.js b/search-in-rotated-sorted-array/byol-han.js
new file mode 100644
index 000000000..3ba1bacf9
--- /dev/null
+++ b/search-in-rotated-sorted-array/byol-han.js
@@ -0,0 +1,46 @@
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
+var search = function (nums, target) {
+  let left = 0;
+  let right = nums.length - 1;
+
+  // Continue searching while the window is valid
+  while (left <= right) {
+    // Find the middle index
+    let mid = Math.floor((left + right) / 2);
+
+    // If the target is found at mid, return the index
+    if (nums[mid] === target) {
+      return mid;
+    }
+
+    // Check if the left half is sorted
+    if (nums[left] <= nums[mid]) {
+      // If target is in the range of the sorted left half
+      if (nums[left] <= target && target < nums[mid]) {
+        // Move the right pointer to just before mid
+        right = mid - 1;
+      } else {
+        // Target must be in the right half
+        left = mid + 1;
+      }
+
+      // Otherwise, the right half must be sorted
+    } else {
+      // If target is in the range of the sorted right half
+      if (nums[mid] < target && target <= nums[right]) {
+        // Move the left pointer to just after mid
+        left = mid + 1;
+      } else {
+        // Target must be in the left half
+        right = mid - 1;
+      }
+    }
+  }
+
+  // If the loop ends, target is not in the array
+  return -1;
+};

From d67575af0e319c9845738cf94c0f09d2f3d0195f Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sat, 7 Jun 2025 02:13:21 -0700
Subject: [PATCH 3/6] course-schedule solution

---
 course-schedule/byol-han.js | 48 +++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 course-schedule/byol-han.js

diff --git a/course-schedule/byol-han.js b/course-schedule/byol-han.js
new file mode 100644
index 000000000..170face62
--- /dev/null
+++ b/course-schedule/byol-han.js
@@ -0,0 +1,48 @@
+/**
+ * @param {number} numCourses
+ * @param {number[][]} prerequisites
+ * @return {boolean}
+ */
+var canFinish = function (numCourses, prerequisites) {
+  if (numCourses === 1) return true; // 과목이 1개면 무조건 수강 가능
+
+  let adjList = new Map(); // 각 과목에 대해 선행 과목들을 저장하는 인접 리스트
+  let visited = new Set(); // 이미 수강 가능한 것으로 확인된 과목들
+  let path = new Set(); // 현재 DFS 경로에 포함된 과목들 (사이클 확인용)
+
+  // 모든 과목을 인접 리스트에 초기화
+  for (let i = 0; i < numCourses; i++) {
+    adjList.set(i, []);
+  }
+
+  // prerequisite 정보를 기반으로 인접 리스트 구성
+  for (let i = 0; i < prerequisites.length; i++) {
+    // [0, 1]은 0을 듣기 위해 1을 먼저 들어야 함
+    adjList.get(prerequisites[i][0]).push(prerequisites[i][1]);
+  }
+
+  // DFS 함수: 해당 course를 수강할 수 있는지 확인
+  const canTake = (course) => {
+    if (visited.has(course)) return true; // 이미 확인된 코스는 재확인 필요 없음
+    if (path.has(course)) return false; // 현재 DFS 경로에 course가 있다면 사이클 발생
+
+    path.add(course); // 현재 경로에 course 추가
+
+    let preCourses = adjList.get(course); // course를 듣기 위한 선행 과목들
+    for (let i = 0; i < preCourses.length; i++) {
+      if (!canTake(preCourses[i])) return false; // 선행 과목 중 하나라도 불가능하면 종료
+    }
+
+    path.delete(course); // 경로에서 제거 (백트래킹)
+    visited.add(course); // 수강 가능한 것으로 확인
+    return true;
+  };
+
+  // 모든 과목에 대해 수강 가능한지 확인
+  for (let i = 0; i < numCourses; i++) {
+    path = new Set(); // 새로운 DFS 탐색이므로 경로 초기화
+    if (!canTake(i)) return false; // 한 과목이라도 못 들으면 false
+  }
+
+  return true; // 모든 과목 수강 가능
+};

From 0d1478876cc336dfe5f53fe6ad718c079273cb7c Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sat, 7 Jun 2025 02:28:45 -0700
Subject: [PATCH 4/6] jump-game solution

---
 jump-game/byol-han.js | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 jump-game/byol-han.js

diff --git a/jump-game/byol-han.js b/jump-game/byol-han.js
new file mode 100644
index 000000000..92b0b2b2a
--- /dev/null
+++ b/jump-game/byol-han.js
@@ -0,0 +1,26 @@
+/**
+ * https://leetcode.com/problems/jump-game/description/
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var canJump = function (nums) {
+  let maxReach = 0; // 현재까지 도달할 수 있는 최대 인덱스
+
+  for (let i = 0; i < nums.length; i++) {
+    // 현재 위치가 도달 가능한 최대 거리보다 멀다면 끝에 도달할 수 없음
+    if (i > maxReach) {
+      return false;
+    }
+
+    // 현재 위치에서 갈 수 있는 최대 위치 업데이트
+    maxReach = Math.max(maxReach, i + nums[i]);
+
+    // 최종 목적지에 도달 가능하면 true 바로 반환
+    if (maxReach >= nums.length - 1) {
+      return true;
+    }
+  }
+
+  // 반복문 끝나도 못 도달한 경우
+  return false;
+};

From 718fc34a7efbbbe1ca7e6fa74d030793c22b587a Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sat, 7 Jun 2025 02:45:06 -0700
Subject: [PATCH 5/6] merge-k-sorted-lists solution

---
 merge-k-sorted-lists/byol-han.js | 49 ++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
 create mode 100644 merge-k-sorted-lists/byol-han.js

diff --git a/merge-k-sorted-lists/byol-han.js b/merge-k-sorted-lists/byol-han.js
new file mode 100644
index 000000000..9f218f2f9
--- /dev/null
+++ b/merge-k-sorted-lists/byol-han.js
@@ -0,0 +1,49 @@
+/**
+ * https://leetcode.com/problems/merge-k-sorted-lists/description/
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode[]} lists
+ * @return {ListNode}
+ */
+var mergeKLists = function (lists) {
+  if (lists.length === 0) {
+    return null;
+  }
+
+  while (lists.length > 1) {
+    const merged = [];
+    const size = lists.length;
+
+    for (let i = 0; i < size; i += 2) {
+      const l1 = lists[i];
+      const l2 = i + 1 < lists.length ? lists[i + 1] : null;
+      merged.push(mergeLists(l1, l2));
+    }
+
+    lists = merged;
+  }
+
+  return lists[0];
+};
+
+function mergeLists(l1, l2) {
+  const head = new ListNode(0);
+  let cur = head;
+  while (l1 !== null && l2 !== null) {
+    if (l1.val < l2.val) {
+      cur.next = l1;
+      l1 = l1.next;
+    } else {
+      cur.next = l2;
+      l2 = l2.next;
+    }
+    cur = cur.next;
+  }
+  cur.next = l1 === null ? l2 : l1;
+  return head.next;
+}

From b57c9b30124b2f9e89d8502f0c5f2f3fc1c7ffb7 Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sat, 7 Jun 2025 02:48:54 -0700
Subject: [PATCH 6/6] add link

---
 course-schedule/byol-han.js                | 1 +
 search-in-rotated-sorted-array/byol-han.js | 1 +
 2 files changed, 2 insertions(+)

diff --git a/course-schedule/byol-han.js b/course-schedule/byol-han.js
index 170face62..cf6ec99bd 100644
--- a/course-schedule/byol-han.js
+++ b/course-schedule/byol-han.js
@@ -1,4 +1,5 @@
 /**
+ * https://leetcode.com/problems/course-schedule/description/
  * @param {number} numCourses
  * @param {number[][]} prerequisites
  * @return {boolean}
diff --git a/search-in-rotated-sorted-array/byol-han.js b/search-in-rotated-sorted-array/byol-han.js
index 3ba1bacf9..df34c0c82 100644
--- a/search-in-rotated-sorted-array/byol-han.js
+++ b/search-in-rotated-sorted-array/byol-han.js
@@ -1,4 +1,5 @@
 /**
+ * https://leetcode.com/problems/search-in-rotated-sorted-array/
  * @param {number[]} nums
  * @param {number} target
  * @return {number}