From 9ee29662d9daac8b0776aa60c5756fb4b5d44fa9 Mon Sep 17 00:00:00 2001
From: Jeongwon Na <ge95lis@tum.de>
Date: Sat, 18 Oct 2025 11:19:03 +0200
Subject: [PATCH 1/4] meeting rooms solution

---
 meeting-rooms/njngwn.java | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 meeting-rooms/njngwn.java

diff --git a/meeting-rooms/njngwn.java b/meeting-rooms/njngwn.java
new file mode 100644
index 000000000..4e0cc8480
--- /dev/null
+++ b/meeting-rooms/njngwn.java
@@ -0,0 +1,30 @@
+/**
+ * Definition of Interval:
+ * public class Interval {
+ *     int start, end;
+ *     Interval(int start, int end) {
+ *         this.start = start;
+ *         this.end = end;
+ *     }
+ * }
+ */
+
+public class Solution {
+    /**
+     * @param intervals: an array of meeting time intervals
+     * @return: if a person could attend all meetings
+     */
+    public boolean canAttendMeetings(List<Interval> intervals) {
+        // Write your code here
+        intervals.sort((a, b) -> a.start - b.start);    // sort by start time
+
+        int prevEndTime = 0;
+        for (Interval meeting : intervals) {
+            if (meeting.start < prevEndTime) {
+                return false;
+            }
+            prevEndTime = meeting.end;
+        }
+        return true;
+    }
+}
\ No newline at end of file

From 42275afa889e8f3bbc0ad000119ba8ecca84bec9 Mon Sep 17 00:00:00 2001
From: Jeongwon Na <ge95lis@tum.de>
Date: Sat, 18 Oct 2025 11:22:40 +0200
Subject: [PATCH 2/4] add line

---
 meeting-rooms/njngwn.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meeting-rooms/njngwn.java b/meeting-rooms/njngwn.java
index 4e0cc8480..af5e7d040 100644
--- a/meeting-rooms/njngwn.java
+++ b/meeting-rooms/njngwn.java
@@ -27,4 +27,4 @@ public boolean canAttendMeetings(List<Interval> intervals) {
         }
         return true;
     }
-}
\ No newline at end of file
+}

From a8fda8fbdfec20ebfbaaa0cb95b398826d768feb Mon Sep 17 00:00:00 2001
From: Jeongwon Na <ge95lis@tum.de>
Date: Sat, 18 Oct 2025 11:48:07 +0200
Subject: [PATCH 3/4] lca solution

---
 .../njngwn.java                               | 23 +++++++++++++++++++
 1 file changed, 23 insertions(+)
 create mode 100644 lowest-common-ancestor-of-a-binary-search-tree/njngwn.java

diff --git a/lowest-common-ancestor-of-a-binary-search-tree/njngwn.java b/lowest-common-ancestor-of-a-binary-search-tree/njngwn.java
new file mode 100644
index 000000000..bd679d020
--- /dev/null
+++ b/lowest-common-ancestor-of-a-binary-search-tree/njngwn.java
@@ -0,0 +1,23 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode(int x) { val = x; }
+ * }
+ */
+
+class Solution {
+    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
+        if (root.val == p.val || root.val == q.val) return root;
+
+        if (p.val < root.val && q.val < root.val) {
+            return lowestCommonAncestor(root.left, p, q);
+        } else if (p.val > root.val && q.val > root.val) {
+            return lowestCommonAncestor(root.right, p, q);
+        } else {
+            return root;
+        }
+    }
+}

From 699a5baecd19ab79aaa15cbf628d3f416a177f07 Mon Sep 17 00:00:00 2001
From: Jeongwon Na <ge95lis@tum.de>
Date: Sat, 18 Oct 2025 12:15:07 +0200
Subject: [PATCH 4/4] kth-smallest-element-in-a-bst solution

---
 kth-smallest-element-in-a-bst/njngwn.java | 37 +++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 kth-smallest-element-in-a-bst/njngwn.java

diff --git a/kth-smallest-element-in-a-bst/njngwn.java b/kth-smallest-element-in-a-bst/njngwn.java
new file mode 100644
index 000000000..2843909d3
--- /dev/null
+++ b/kth-smallest-element-in-a-bst/njngwn.java
@@ -0,0 +1,37 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ *     int val;
+ *     TreeNode left;
+ *     TreeNode right;
+ *     TreeNode() {}
+ *     TreeNode(int val) { this.val = val; }
+ *     TreeNode(int val, TreeNode left, TreeNode right) {
+ *         this.val = val;
+ *         this.left = left;
+ *         this.right = right;
+ *     }
+ * }
+ */
+class Solution {
+    int cnt = 0;
+    int result = 0;
+
+    public int kthSmallest(TreeNode root, int k) {
+        cnt = k;
+        traverseInOrder(root);
+        return result;
+    }
+
+    public void traverseInOrder (TreeNode node) {
+        if (node == null) return;
+
+        if (node.left != null) traverseInOrder(node.left);
+        cnt--;
+        if (cnt == 0) {
+            result = node.val;
+            return;
+        }
+        if (node.right != null) traverseInOrder(node.right);
+    }
+}