From 2a9a1c91c38dd1d33df29724132cbea0219e89b0 Mon Sep 17 00:00:00 2001
From: kim <se6816@naver.com>
Date: Sat, 17 Jan 2026 23:50:10 +0900
Subject: [PATCH 1/4] invert binary tree

---
 invert-binary-tree/se6816.java | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 invert-binary-tree/se6816.java

diff --git a/invert-binary-tree/se6816.java b/invert-binary-tree/se6816.java
new file mode 100644
index 0000000000..9d2b7c493a
--- /dev/null
+++ b/invert-binary-tree/se6816.java
@@ -0,0 +1,21 @@
+class Solution {
+    public TreeNode invertTree(TreeNode root) {
+        if(root == null) return root;
+        Queue<TreeNode> que = new ArrayDeque<>();
+        que.add(root);
+
+        while(!que.isEmpty()) {
+            TreeNode node = que.poll();
+            TreeNode tempNode = node.left;
+            node.left = node.right;
+            node.right = tempNode;
+            if(node.left != null) {
+                que.add(node.left);
+            }
+            if(node.right != null) {
+                que.add(node.right);
+            }
+        }
+        return root;
+    }
+}

From f1e45b7e4b6385163cc02f7c0c093e2cd8bf6e0a Mon Sep 17 00:00:00 2001
From: kim <se6816@naver.com>
Date: Sat, 17 Jan 2026 23:51:09 +0900
Subject: [PATCH 2/4] search in rotated sorted array

---
 search-in-rotated-sorted-array/se6816.java | 46 ++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 search-in-rotated-sorted-array/se6816.java

diff --git a/search-in-rotated-sorted-array/se6816.java b/search-in-rotated-sorted-array/se6816.java
new file mode 100644
index 0000000000..771e50db15
--- /dev/null
+++ b/search-in-rotated-sorted-array/se6816.java
@@ -0,0 +1,46 @@
+class Solution {
+    public int search(int[] nums, int target) {
+        int firstIdx = binarySearch(nums);
+        int result = 0;
+        if (firstIdx == 0) {
+            return binarySearch(target, nums, 0, nums.length - 1);
+        } else if (target >= nums[0]) {
+            return binarySearch(target, nums, 0, firstIdx);
+        } else {
+            return binarySearch(target, nums, firstIdx, nums.length - 1);
+        }
+    }
+
+    public int binarySearch(int[] nums) {
+            int start = 0;
+            int end = nums.length -1;
+            while(start < end) {
+                int mid = (start + end) / 2;
+                if(nums[mid] < nums[end]) {
+                    end = mid;
+                } else {
+                    start = mid + 1;
+                }
+            }
+            return start;
+    }
+
+    public int binarySearch(int target, int[] nums, int start, int end) {
+            int result = -1;
+            while(start <= end) {
+                int mid = (start + end) / 2;
+                if(nums[mid] > target) {
+                    end = mid - 1;
+                } else if(nums[mid] < target){
+                    start = mid + 1;
+                } else {
+                    result = mid;
+                    break;
+                }
+            }
+
+            return result;
+    }
+        
+    
+}

From 388e17d919211887ada94ca6b011b4fa42a02773 Mon Sep 17 00:00:00 2001
From: kim <se6816@naver.com>
Date: Sat, 17 Jan 2026 23:52:04 +0900
Subject: [PATCH 3/4] jump game

---
 jump-game/se6816.java | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 jump-game/se6816.java

diff --git a/jump-game/se6816.java b/jump-game/se6816.java
new file mode 100644
index 0000000000..6eed680d64
--- /dev/null
+++ b/jump-game/se6816.java
@@ -0,0 +1,27 @@
+class Solution {
+    public boolean canJump(int[] nums) {
+        boolean[] visited= new boolean[nums.length];
+        dfs(visited, nums, 0);
+        return visited[nums.length - 1];
+    }
+    public void dfs(boolean[] visited, int[] nums, int target) {
+        if(visited[nums.length -1]) {
+            return;
+        }
+        if(visited[target]) {
+            return;
+        }
+
+        visited[target] = true;
+
+        int maxDist = nums[target];
+        for(int i = maxDist; i > 0; i--) {
+            int nextIdx = target + i;
+            if(nextIdx > nums.length - 1) {
+                continue;
+            }
+
+            dfs(visited, nums, nextIdx);
+        }
+    }
+}

From a40929784a6858dbbd4d0748eadd5d69a6507f4d Mon Sep 17 00:00:00 2001
From: kim <se6816@naver.com>
Date: Sat, 17 Jan 2026 23:53:23 +0900
Subject: [PATCH 4/4] merge k sorted lists

---
 merge-k-sorted-lists/se6816.java | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 merge-k-sorted-lists/se6816.java

diff --git a/merge-k-sorted-lists/se6816.java b/merge-k-sorted-lists/se6816.java
new file mode 100644
index 0000000000..c844d041eb
--- /dev/null
+++ b/merge-k-sorted-lists/se6816.java
@@ -0,0 +1,28 @@
+
+class Solution {
+    public ListNode mergeKLists(ListNode[] lists) {
+            ListNode list= new ListNode(0); // head
+            ListNode curr=list;
+            PriorityQueue<ListNode> pq=new PriorityQueue<ListNode>((l1, l2)->{
+                return l1.val - l2.val;
+            });
+            for(int i=0; i<lists.length;i++){
+                if(lists[i]!=null){
+                    pq.offer(lists[i]);
+                }
+            }
+            while(!pq.isEmpty()){
+                ListNode temp = pq.poll();
+                curr.next=new ListNode(temp.val);
+                curr=curr.next;
+                temp=temp.next;
+                if(temp!=null){
+                    pq.offer(temp);
+                }
+
+            }
+            return list.next;
+                
+        
+    }
+}