diff --git "a/topic04/submit/LC1376_\346\233\276\344\272\246\350\214\227.cpp" "b/topic04/submit/LC1376_\346\233\276\344\272\246\350\214\227.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..038874584283298ac88824991fb2cfe0dfaf5e7a
--- /dev/null
+++ "b/topic04/submit/LC1376_\346\233\276\344\272\246\350\214\227.cpp"
@@ -0,0 +1,21 @@
+class Solution {
+public:
+    int numOfMinutes(int n, int headID, vector<int>& manager, vector<int>& informTime) {
+        vector<vector<int>>subordinates(n);
+        for(int i=0;i<n;++i){
+            if(manager[i] != -1){
+                subordinates[manager[i]].push_back(i);
+            }
+        }
+
+        return dfs(headID,subordinates,informTime);
+    }
+private:
+    int dfs(int node,const vector<vector<int>>& subordinates,const vector<int>& informTime){
+        int maxTime = 0;
+        for(int sub:subordinates[node]){
+            maxTime = max(maxTime,dfs(sub,subordinates,informTime));
+        }
+        return informTime[node]+maxTime;
+    }
+};
\ No newline at end of file
diff --git "a/topic04/submit/LC1443_\346\233\276\344\272\246\350\214\227.cpp" "b/topic04/submit/LC1443_\346\233\276\344\272\246\350\214\227.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..c93e1ccbb7a8ebdbaf08550158b4ad2bab7f1538
--- /dev/null
+++ "b/topic04/submit/LC1443_\346\233\276\344\272\246\350\214\227.cpp"
@@ -0,0 +1,22 @@
+class Solution {
+public:
+    int minTime(int n, vector<vector<int>>& edges, vector<bool>& hasApple) {
+        vector<vector<int>> adj(n);
+        for (auto& e : edges) {
+            adj[e[0]].push_back(e[1]);
+            adj[e[1]].push_back(e[0]);
+        }
+        function<int(int, int)> dfs = [&](int node, int parent) {
+            int time = 0;
+            for (int child : adj[node]) {
+                if (child == parent) continue;
+                int childTime = dfs(child, node);
+                if (childTime > 0 || hasApple[child]) {
+                    time += childTime + 2;
+                }
+            }
+            return time;
+        };
+        return dfs(0, -1);
+    }
+};
\ No newline at end of file
diff --git "a/topic04/submit/LC310_\346\233\276\344\272\246\350\214\227.cpp" "b/topic04/submit/LC310_\346\233\276\344\272\246\350\214\227.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..2edc15534f0b359676342455d9e0f3d7783cbfa8
--- /dev/null
+++ "b/topic04/submit/LC310_\346\233\276\344\272\246\350\214\227.cpp"
@@ -0,0 +1,49 @@
+#include <vector>
+#include <queue>
+#include <unordered_set>
+using namespace std;
+
+class Solution {
+public:
+    vector<int> findMinHeightTrees(int n, vector<vector<int>>& edges) {
+        if (n == 1) return {0};
+
+        vector<unordered_set<int>> adj(n);
+        for (auto& e : edges) {
+            adj[e[0]].insert(e[1]);
+            adj[e[1]].insert(e[0]);
+        }
+
+        queue<int> q;
+        for (int i = 0; i < n; ++i) {
+            if (adj[i].size() == 1) {
+                q.push(i);
+            }
+        }
+
+        int remaining = n;
+        while (remaining > 2) {
+            int size = q.size();
+            remaining -= size;
+
+            for (int i = 0; i < size; ++i) {
+                int leaf = q.front();
+                q.pop();
+
+                int neighbor = *adj[leaf].begin();
+                adj[neighbor].erase(leaf);
+
+                if (adj[neighbor].size() == 1) {
+                    q.push(neighbor);
+                }
+            }
+        }
+
+        vector<int> res;
+        while (!q.empty()) {
+            res.push_back(q.front());
+            q.pop();
+        }
+        return res;
+    }
+};
\ No newline at end of file
diff --git "a/topic04/submit/LC687_\346\233\276\344\272\246\350\214\227.cpp" "b/topic04/submit/LC687_\346\233\276\344\272\246\350\214\227.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..e6f9c11620f308aa7931e665706405164a5acff8
--- /dev/null
+++ "b/topic04/submit/LC687_\346\233\276\344\272\246\350\214\227.cpp"
@@ -0,0 +1,26 @@
+#include <algorithm>
+using namespace std;
+
+class Solution {
+private:
+    int max_len = 0;
+
+    int dfs(TreeNode* root) {
+        if (!root) return 0;
+
+        int left = dfs(root->left);
+        int right = dfs(root->right);
+
+        int left_contribution = (root->left && root->left->val == root->val) ? left + 1 : 0;
+        int right_contribution = (root->right && root->right->val == root->val) ? right + 1 : 0;
+
+        max_len = max(max_len, left_contribution + right_contribution);
+        return max(left_contribution, right_contribution);
+    }
+
+public:
+    int longestUnivaluePath(TreeNode* root) {
+        dfs(root);
+        return max_len;
+    }
+};
\ No newline at end of file