From 761a2376417aa95c9ede8e0be4bc592fa60b2167 Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sun, 25 May 2025 13:51:30 -0700
Subject: [PATCH 1/6] clone graph solution

---
 clone-graph/byol-han.js | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 clone-graph/byol-han.js

diff --git a/clone-graph/byol-han.js b/clone-graph/byol-han.js
new file mode 100644
index 000000000..9c20dad67
--- /dev/null
+++ b/clone-graph/byol-han.js
@@ -0,0 +1,37 @@
+/**
+ * https://leetcode.com/problems/clone-graph/
+ * // Definition for a _Node.
+ * function _Node(val, neighbors) {
+ *    this.val = val === undefined ? 0 : val;
+ *    this.neighbors = neighbors === undefined ? [] : neighbors;
+ * };
+ * 시간 복잡도: O(N) — 노드 수만큼 순회
+ * 공간 복잡도: O(N) — visited 맵과 재귀 호출 스택
+ */
+
+/**
+ * @param {_Node} node
+ * @return {_Node}
+ */
+var cloneGraph = function (node) {
+  if (!node) return null;
+
+  const visited = new Map();
+
+  const dfs = (n) => {
+    if (visited.has(n)) {
+      return visited.get(n);
+    }
+
+    const clone = new Node(n.val);
+    visited.set(n, clone);
+
+    for (let neighbor of n.neighbors) {
+      clone.neighbors.push(dfs(neighbor));
+    }
+
+    return clone;
+  };
+
+  return dfs(node);
+};

From 9e34767733d692c677d9ecbd467b952da07576c0 Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sun, 25 May 2025 13:54:57 -0700
Subject: [PATCH 2/6] palindromic-substrings solution

---
 palindromic-substrings/byol-han.js | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 palindromic-substrings/byol-han.js

diff --git a/palindromic-substrings/byol-han.js b/palindromic-substrings/byol-han.js
new file mode 100644
index 000000000..69e7cdd55
--- /dev/null
+++ b/palindromic-substrings/byol-han.js
@@ -0,0 +1,24 @@
+/**
+ * https://leetcode.com/problems/palindromic-substrings/submissions/1644425061/
+ * @param {string} s
+ * @return {number}
+ */
+var countSubstrings = function (s) {
+  let count = 0;
+
+  // Helper function to expand around the center
+  function expandAroundCenter(left, right) {
+    while (left >= 0 && right < s.length && s[left] === s[right]) {
+      count++; // Found a palindrome
+      left--;
+      right++;
+    }
+  }
+
+  for (let i = 0; i < s.length; i++) {
+    expandAroundCenter(i, i); // Odd-length palindromes
+    expandAroundCenter(i, i + 1); // Even-length palindromes
+  }
+
+  return count;
+};

From 6fda5a7696d79f7f2a001c67a7d054044925d1f2 Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sun, 25 May 2025 13:56:57 -0700
Subject: [PATCH 3/6] longest-common-subsequence solution

---
 longest-common-subsequence/byol-han.js | 29 ++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 longest-common-subsequence/byol-han.js

diff --git a/longest-common-subsequence/byol-han.js b/longest-common-subsequence/byol-han.js
new file mode 100644
index 000000000..a3afa3191
--- /dev/null
+++ b/longest-common-subsequence/byol-han.js
@@ -0,0 +1,29 @@
+/**
+ * https://leetcode.com/problems/longest-common-subsequence/submissions/1644426037/
+ * @param {string} text1
+ * @param {string} text2
+ * @return {number}
+ */
+var longestCommonSubsequence = function (text1, text2) {
+  const m = text1.length;
+  const n = text2.length;
+
+  // Create 2D array initialized with 0
+  const dp = Array.from({ length: m + 1 }, () => Array(n + 1).fill(0));
+
+  // Fill the dp table
+  for (let i = 1; i <= m; i++) {
+    for (let j = 1; j <= n; j++) {
+      if (text1[i - 1] === text2[j - 1]) {
+        // Characters match
+        dp[i][j] = dp[i - 1][j - 1] + 1;
+      } else {
+        // No match, take the max from left or top cell
+        dp[i][j] = Math.max(dp[i - 1][j], dp[i][j - 1]);
+      }
+    }
+  }
+
+  // The length of the longest common subsequence
+  return dp[m][n];
+};

From 7bc75e58ad310fe0502d0ff7422ef40615bfd5ca Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sat, 31 May 2025 01:28:17 -0700
Subject: [PATCH 4/6] liked list cycle solution

---
 linked-list-cycle/byol-han.js | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 linked-list-cycle/byol-han.js

diff --git a/linked-list-cycle/byol-han.js b/linked-list-cycle/byol-han.js
new file mode 100644
index 000000000..9071f7be7
--- /dev/null
+++ b/linked-list-cycle/byol-han.js
@@ -0,0 +1,34 @@
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val) {
+ *     this.val = val;
+ *     this.next = null;
+ * }
+ */
+
+/**
+ * @param {ListNode} head
+ * @return {boolean}
+ */
+var hasCycle = function (head) {
+  // 리스트가 비어 있거나 노드가 하나뿐이면 사이클이 있을 수 없음
+  if (!head || !head.next) return false;
+
+  // 두 포인터 초기화: slow는 한 칸씩, fast는 두 칸씩 이동
+  let slow = head;
+  let fast = head.next;
+
+  // fast와 slow가 만날 때까지 반복
+  while (fast !== slow) {
+    // fast가 끝에 도달하면 사이클이 없음
+    if (!fast || !fast.next) return false;
+
+    // slow는 한 칸 이동
+    slow = slow.next;
+    // fast는 두 칸 이동
+    fast = fast.next.next;
+  }
+
+  // fast와 slow가 만났다면 사이클이 있음
+  return true;
+};

From 80ec48415d7cb75ede15bc93abc9f53348629626 Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sat, 31 May 2025 01:39:33 -0700
Subject: [PATCH 5/6] maximum product subarray solution

---
 maximum-product-subarray/byol-han.js | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 maximum-product-subarray/byol-han.js

diff --git a/maximum-product-subarray/byol-han.js b/maximum-product-subarray/byol-han.js
new file mode 100644
index 000000000..5e9b329c8
--- /dev/null
+++ b/maximum-product-subarray/byol-han.js
@@ -0,0 +1,28 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var maxProduct = function (nums) {
+  // 최대 곱을 저장할 변수
+  let maxProduct = nums[0];
+  // 현재 위치까지의 최대 곱과 최소 곱을 저장할 변수
+  let currentMax = nums[0];
+  let currentMin = nums[0];
+
+  // 배열의 두 번째 원소부터 순회
+  for (let i = 1; i < nums.length; i++) {
+    const num = nums[i];
+
+    // 음수를 곱할 경우 최대와 최소가 바뀔 수 있으므로 미리 저장
+    const tempMax = currentMax;
+
+    // 현재 숫자와 곱했을 때의 최대/최소 값을 계산
+    currentMax = Math.max(num, num * currentMax, num * currentMin);
+    currentMin = Math.min(num, num * tempMax, num * currentMin);
+
+    // 전체 최대 곱을 업데이트
+    maxProduct = Math.max(maxProduct, currentMax);
+  }
+
+  return maxProduct;
+};

From 97165918e20a39868fec5b7b2ce9ccccb773ea4f Mon Sep 17 00:00:00 2001
From: byol-han <byolhandev@gmail.com>
Date: Sat, 31 May 2025 01:41:37 -0700
Subject: [PATCH 6/6] sum-of-two-integers solution

---
 sum-of-two-integers/byol-han.js | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 sum-of-two-integers/byol-han.js

diff --git a/sum-of-two-integers/byol-han.js b/sum-of-two-integers/byol-han.js
new file mode 100644
index 000000000..c6d6cfc23
--- /dev/null
+++ b/sum-of-two-integers/byol-han.js
@@ -0,0 +1,22 @@
+/**
+ * https://leetcode.com/problems/sum-of-two-integers/submissions/1649575939/
+ * @param {number} a
+ * @param {number} b
+ * @return {number}
+ */
+var getSum = function (a, b) {
+  while (b !== 0) {
+    // a와 b의 합에서 자리올림(carry)을 제외한 값 계산 (XOR 연산)
+    let sum = a ^ b;
+
+    // 자리올림(carry)을 계산 (AND 연산 후 왼쪽으로 한 비트 이동)
+    let carry = (a & b) << 1;
+
+    // 새로운 a는 sum, 새로운 b는 carry가 됨
+    a = sum;
+    b = carry;
+  }
+
+  // carry가 0이 되면 더할 게 없으므로 최종 결과 a 반환
+  return a;
+};