diff --git a/CPP/dp trapping rainwater.cpp b/CPP/dp trapping rainwater.cpp
new file mode 100644
index 0000000..d01b63a
--- /dev/null
+++ b/CPP/dp trapping rainwater.cpp	
@@ -0,0 +1,28 @@
+class Solution {
+public:
+    int trap(vector<int>& height) {
+       int n=height.size();
+        vector<int> mxl(n);// maximum height to the left
+        mxl[0]=height[0];
+       //mxl.push_back(height[0]);
+        for(int i=1;i<n;i++)
+        {
+            int mx = max(mxl[i-1], height[i]);
+            mxl[i] = mx;
+        }
+        
+        int mxr[n];
+         mxr[n-1]=height[n-1];
+        for(int i=n-2;i>=0;i--)
+        {
+            int nx=max(height[i],mxr[i+1]);
+            mxr[i]=nx;
+        }
+        int sum=0;
+        for(int i=1;i< n-1;i++)
+        {
+            sum+=max(min(mxr[i],mxl[i])-height[i], 0);
+        }
+        return sum;
+    }
+};