diff --git a/invert-binary-tree/juhui-jeong.java b/invert-binary-tree/juhui-jeong.java
index d03d60a5f1..1ebb6c6fea 100644
--- a/invert-binary-tree/juhui-jeong.java
+++ b/invert-binary-tree/juhui-jeong.java
@@ -1,6 +1,7 @@
 /*
- * 시간 복잡도: O(1)
- * 공간 복잡도: O(1)
+이전 풀이
+ * 시간 복잡도: O(n)
+ * 공간 복잡도: O(n)
  */
 public class Solution {
     public TreeNode invertTree(TreeNode root) {
@@ -30,3 +31,30 @@ public TreeNode invertTree(TreeNode root) {
         return root;
     }
 }
+
+/**
+ * 시간 복잡도: O(n)
+ * 공간 복잡도: O(n)
+ * DFS 풀이
+ */
+class Solution {
+    public TreeNode invertTree(TreeNode root) {
+        if (root == null) return null;
+
+        Deque<TreeNode> stack = new ArrayDeque<>();
+        stack.push(root);
+
+        while(!stack.isEmpty()) {
+            TreeNode cur = stack.pop();
+            
+            TreeNode temp = cur.left;
+            cur.left = cur.right;
+            cur.right = temp;
+ 
+            if (cur.left != null) stack.push(cur.left);
+
+            if (cur.right != null) stack.push(cur.right);
+        }
+        return root;
+    }
+}
diff --git a/search-in-rotated-sorted-array/juhui-jeong.java b/search-in-rotated-sorted-array/juhui-jeong.java
new file mode 100644
index 0000000000..89bec9ca9a
--- /dev/null
+++ b/search-in-rotated-sorted-array/juhui-jeong.java
@@ -0,0 +1,34 @@
+/**
+ * 시간 복잡도: O(log n)
+ * 공간 복잡도: O(1)
+ */
+class Solution {
+    public int search(int[] nums, int target) {
+        int low = 0;
+        int high = nums.length - 1;
+
+        while (low <= high) {
+            int mid = (low + high) / 2;
+            
+            if (nums[mid] == target) {
+                return mid;
+            }
+            // 왼쪽 구간이 정렬된 경우
+            if (nums[low] <= nums[mid]) {
+                if (nums[low] <= target && target < nums[mid]) {
+                    high = mid - 1;
+                } else {
+                    low = mid + 1;
+                }
+            // 오른쪽 구간이 정렬된 경우
+            } else {
+                if (nums[mid] < target && target <= nums[high]) {
+                    low = mid + 1;
+                } else {
+                    high = mid - 1;
+                }
+            }
+        }
+        return -1;
+    }
+}