diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index aa4302b..1ec84c5 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -13,7 +13,7 @@
             "state": {
               "type": "markdown",
               "state": {
-                "file": "OJ notes/pages/Elementary Math Problems.md",
+                "file": "OJ notes/pages/Leetcode Binary-Tree-Level-Order-Traversal.md",
                 "mode": "preview",
                 "backlinks": false,
                 "source": true
@@ -50,7 +50,7 @@
             "state": {
               "type": "search",
               "state": {
-                "query": "tag:#problem_collection",
+                "query": "bfs",
                 "matchingCase": false,
                 "explainSearch": false,
                 "collapseAll": true,
@@ -96,7 +96,7 @@
             "state": {
               "type": "backlink",
               "state": {
-                "file": "OJ notes/pages/Elementary Math Problems.md",
+                "file": "OJ notes/pages/Leetcode Binary-Tree-Level-Order-Traversal.md",
                 "collapseAll": false,
                 "extraContext": false,
                 "sortOrder": "alphabetical",
@@ -113,7 +113,7 @@
             "state": {
               "type": "outgoing-link",
               "state": {
-                "file": "OJ notes/pages/Elementary Math Problems.md",
+                "file": "OJ notes/pages/Leetcode Binary-Tree-Level-Order-Traversal.md",
                 "linksCollapsed": false,
                 "unlinkedCollapsed": true
               }
@@ -143,7 +143,7 @@
             "state": {
               "type": "outline",
               "state": {
-                "file": "OJ notes/pages/Elementary Math Problems.md"
+                "file": "OJ notes/pages/Leetcode Binary-Tree-Level-Order-Traversal.md"
               }
             }
           }
@@ -156,17 +156,17 @@
   "ribbon": {
     "mostRecentAction": ""
   },
-  "active": "9fea4d6a3fb7b065",
+  "active": "734cb4b36b9fd11f",
   "lastOpenFiles": [
+    "OJ notes/pages/Breadth First Search.md",
     "OJ notes/OJ-index.md",
+    "Index.md",
+    "Untitled.md",
+    "OJ notes/pages/Elementary Math Problems.md",
     "Wiki/pages/Gentoo log parser.md",
     "Wiki/Ideas.md",
     "Wiki/Wiki-Index.md",
     "Wiki/Software Index.md",
-    "Wiki/Notes for CS.md",
-    "Wiki/ChrootMan.md",
-    "OJ notes/pages/Leetcode Linked-List-Cycle.md",
-    "OJ notes/pages/Leetcode Binary-Tree-Level-Order-Traversal.md",
-    "OJ notes/pages/Leetcode 01-Matrix.md"
+    "Wiki/Notes for CS.md"
   ]
 }
\ No newline at end of file
diff --git a/Untitled.md b/Untitled.md
new file mode 100644
index 0000000..e69de29