diff --git "a/exercise/LC 1944_\351\231\210\346\230\240\350\276\211.cpp" "b/exercise/LC 1944_\351\231\210\346\230\240\350\276\211.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..652032b6047ebd459e1150b192334747b17f926d
--- /dev/null
+++ "b/exercise/LC 1944_\351\231\210\346\230\240\350\276\211.cpp"	
@@ -0,0 +1,21 @@
+class Solution {
+public:
+    vector<int> canSeePersonsCount(vector<int>& heights) {
+        int n=heights.size();
+        vector<int>stk;
+        vector<int>ans(n, 0);
+        
+        for(int i=n-1;i>=0;i--){
+            int h1=heights[i];
+            while(!stk.empty()&&stk.back()<h1){ //核心算法，访问栈顶 
+                stk.pop_back();
+                ans[i]+=1;
+            }
+            if(!stk.empty()){
+                ans[i]+=1;
+            }
+            stk.push_back(h1);
+        }
+        return ans;
+    }
+};
diff --git "a/exercise/LC 42_\351\231\210\346\230\240\350\276\211.cpp" "b/exercise/LC 42_\351\231\210\346\230\240\350\276\211.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..41adaaa906fb48ef72a2a946becb1eaca27b3271
--- /dev/null
+++ "b/exercise/LC 42_\351\231\210\346\230\240\350\276\211.cpp"	
@@ -0,0 +1,23 @@
+class Solution {
+public:
+    int trap(vector<int>& height) {
+        int n =height.size();
+        stack<int>st;
+        int nums=0;
+        for(int i=0;i<n;++i){
+            while(!st.empty()&&height[i]>height[st.top()]){
+                int topIdx=st.top();
+                st.pop();
+                if(st.empty()){
+                    break;
+                }
+                int l = st.top();
+                int currWigth = i-l-1;
+                int currHeight = min(height[l],height[i])-height[topIdx];
+                nums += currWigth * currHeight;
+            }
+            st.push(i);
+        }
+        return nums;
+    }
+};
diff --git "a/topic01/submit/LC 496_\351\231\210\346\230\240\350\276\211.cpp" "b/topic01/submit/LC 496_\351\231\210\346\230\240\350\276\211.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..a8137ea1b12accf21722b0ba43b2c83b69898d53
--- /dev/null
+++ "b/topic01/submit/LC 496_\351\231\210\346\230\240\350\276\211.cpp"	
@@ -0,0 +1,22 @@
+class Solution {
+public:
+    vector<int> nextGreaterElement(vector<int>& nums1, vector<int>& nums2) {
+        int n1=nums1.size();
+        int n2=nums2.size();
+        stack<int>st;
+        unordered_map<int,int>hash;
+        vector<int>ans(n1);
+        for(int i=n2-1;i>=0;--i){   //单调栈
+            int num=nums2[i];
+            while(!st.empty() && num>=st.top()){
+                st.pop();
+            }
+            hash[num]=st.empty()?-1:st.top();
+            st.push(num);      //单调栈结束，把答案存入哈希表
+        }
+        for(int i=0;i<n1;++i){
+            ans[i]=hash[nums1[i]];
+        }
+        return ans;
+    }
+};
diff --git "a/topic01/submit/LC 503_\351\231\210\346\230\240\350\276\211.cpp" "b/topic01/submit/LC 503_\351\231\210\346\230\240\350\276\211.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..db23854290c93da26d9a34095830e2d10738b564
--- /dev/null
+++ "b/topic01/submit/LC 503_\351\231\210\346\230\240\350\276\211.cpp"	
@@ -0,0 +1,17 @@
+class Solution {
+public:
+    vector<int> nextGreaterElements(vector<int>& nums) {
+        int n=nums.size();
+        stack<int>st;
+        vector<int>res(n,-1);
+        for(int i=0;i<n*2-1;++i){
+            while(!st.empty()&&nums[i%n]>nums[st.top()]){
+                int topIdx=st.top();
+                st.pop();
+                res[topIdx]=nums[i%n];
+            }
+            st.push(i%n);
+        }
+        return res;
+    }
+};
diff --git "a/topic01/submit/LC 739_\351\231\210\346\230\240\350\276\211.cpp" "b/topic01/submit/LC 739_\351\231\210\346\230\240\350\276\211.cpp"
new file mode 100644
index 0000000000000000000000000000000000000000..4e110fd7311862688e1e6c1bfb48712ec911e41e
--- /dev/null
+++ "b/topic01/submit/LC 739_\351\231\210\346\230\240\350\276\211.cpp"	
@@ -0,0 +1,17 @@
+class Solution {
+public:
+    vector<int> dailyTemperatures(vector<int>& temperatures) {
+        int n=temperatures.size();
+        vector<int>ans(n,0);
+        stack<int>st;
+        for(int i=0;i<n;++i){
+            while(!st.empty()&&temperatures[i]>temperatures[st.top()]){
+                int topIdx=st.top();
+                ans[topIdx]=i-topIdx;
+                st.pop();
+            }
+            st.push(i);
+        }
+        return ans;
+    }
+};