From bb916e17ebea760d870e3b0d79e223fdfa6ecf3e Mon Sep 17 00:00:00 2001
From: hoyeongkwak <ghy2002@hanmail.net>
Date: Sat, 21 Jun 2025 15:07:57 +0900
Subject: [PATCH 1/2] Solutions Week12

---
 non-overlapping-intervals/hoyeongkwak.ts      | 17 +++++
 .../hoyeongkwak.ts                            | 32 +++++++++
 same-tree/hoyeongkwak.ts                      | 23 +++++++
 .../hoyeongkwak.ts                            | 67 +++++++++++++++++++
 4 files changed, 139 insertions(+)
 create mode 100644 non-overlapping-intervals/hoyeongkwak.ts
 create mode 100644 remove-nth-node-from-end-of-list/hoyeongkwak.ts
 create mode 100644 same-tree/hoyeongkwak.ts
 create mode 100644 serialize-and-deserialize-binary-tree/hoyeongkwak.ts

diff --git a/non-overlapping-intervals/hoyeongkwak.ts b/non-overlapping-intervals/hoyeongkwak.ts
new file mode 100644
index 000000000..040523b5f
--- /dev/null
+++ b/non-overlapping-intervals/hoyeongkwak.ts
@@ -0,0 +1,17 @@
+/*
+Time complexity: O(nlogn)
+Space complexity: O(n)
+*/
+function eraseOverlapIntervals(intervals: number[][]): number {
+    intervals.sort((a, b) => a[1] - b[1])
+    let cnt = 0
+    let end = intervals[0][1]
+    for (let i = 1; i < intervals.length; i++) {
+        if (intervals[i][0] < end) {
+            cnt++
+        } else {
+            end = intervals[i][1]
+        }
+    }
+    return cnt
+};
diff --git a/remove-nth-node-from-end-of-list/hoyeongkwak.ts b/remove-nth-node-from-end-of-list/hoyeongkwak.ts
new file mode 100644
index 000000000..9b14b12ae
--- /dev/null
+++ b/remove-nth-node-from-end-of-list/hoyeongkwak.ts
@@ -0,0 +1,32 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+/*
+Time complexity: O(n)
+Space complexity: O(h)
+*/
+function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null {
+    if (head == null) return head
+    const listLength = (node: ListNode | null): number => {
+        if (node == null) return 0
+        return 1 + listLength(node.next)
+    }
+    const nodeLen = listLength(head)
+    let dummy: ListNode = new ListNode(0, head);
+    let node = dummy
+    for (let i = 0; i < nodeLen - n; i++) {
+        if (node.next) {
+            node = node.next
+        }
+    }
+    node.next = node.next.next
+    return dummy.next
+};
diff --git a/same-tree/hoyeongkwak.ts b/same-tree/hoyeongkwak.ts
new file mode 100644
index 000000000..8f940c4d1
--- /dev/null
+++ b/same-tree/hoyeongkwak.ts
@@ -0,0 +1,23 @@
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+/*
+Time complexity: O(m)
+Space complexity: O(h)
+*/
+function isSameTree(p: TreeNode | null, q: TreeNode | null): boolean {
+    if (p == null && q == null) return true
+    if (p == null || q == null) return false
+    if (p.val !== q.val) return false
+    return isSameTree(p.left, q.left) && isSameTree(p.right, q.right)    
+};
diff --git a/serialize-and-deserialize-binary-tree/hoyeongkwak.ts b/serialize-and-deserialize-binary-tree/hoyeongkwak.ts
new file mode 100644
index 000000000..1e204aab6
--- /dev/null
+++ b/serialize-and-deserialize-binary-tree/hoyeongkwak.ts
@@ -0,0 +1,67 @@
+/**
+ * Definition for a binary tree node.
+ * class TreeNode {
+ *     val: number
+ *     left: TreeNode | null
+ *     right: TreeNode | null
+ *     constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.left = (left===undefined ? null : left)
+ *         this.right = (right===undefined ? null : right)
+ *     }
+ * }
+ */
+
+/*
+ * Encodes a tree to a single string.
+ */
+function serialize(root: TreeNode | null): string {
+    /*
+    Time complexity: O(n)
+    Space complexity: O(n)
+    */
+    const strArray = []
+    const dfs = (node: TreeNode): void => {
+        if (node == null) {
+            strArray.push('null')
+            return
+        }
+        strArray.push(node.val)
+        dfs(node.left)
+        dfs(node.right)
+    }
+    dfs(root)
+    return strArray.join(',')
+};
+
+/*
+ * Decodes your encoded data to tree.
+ */
+function deserialize(data: string): TreeNode | null {
+     /*
+    Time complexity: O(n)
+    Space complexity: O(n)
+    */
+    const values = data.split(',')
+    let idx = 0
+    const dfs = (): TreeNode | null => {
+        if (idx >= values.length || values[idx] == 'null') {
+            idx++
+            return null
+        }
+        const node = new TreeNode(+values[idx])
+        idx++
+        node.left = dfs()
+        node.right = dfs()
+        return node
+    }
+
+    return dfs()
+};
+
+
+/**
+ * Your functions will be called as such:
+ * deserialize(serialize(root));
+ */
+ 
\ No newline at end of file

From a456f63d366b6f99937c32940e0434e8dee50ccb Mon Sep 17 00:00:00 2001
From: hoyeongkwak <ghy2002@hanmail.net>
Date: Sat, 21 Jun 2025 15:09:40 +0900
Subject: [PATCH 2/2] last line modify

---
 serialize-and-deserialize-binary-tree/hoyeongkwak.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/serialize-and-deserialize-binary-tree/hoyeongkwak.ts b/serialize-and-deserialize-binary-tree/hoyeongkwak.ts
index 1e204aab6..75abd59e9 100644
--- a/serialize-and-deserialize-binary-tree/hoyeongkwak.ts
+++ b/serialize-and-deserialize-binary-tree/hoyeongkwak.ts
@@ -64,4 +64,4 @@ function deserialize(data: string): TreeNode | null {
  * Your functions will be called as such:
  * deserialize(serialize(root));
  */
- 
\ No newline at end of file
+