Added Trapping Rainwater Question

Upload Your Code/Arrays/trapping_rainwater.cpp

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+// C++ implementation of the approach 
+
+#include <bits/stdc++.h> 
+using namespace std; 
+
+// Function to return the maximum 
+// water that can be stored 
+int maxWater(int arr[], int n) 
+{ 
+    // To store the maximum water 
+    // that can be stored 
+    int res = 0; 
+
+    // For every element of the array 
+    for (int i = 1; i < n - 1; i++) { 
+
+        // Find the maximum element on its left 
+        int left = arr[i]; 
+        for (int j = 0; j < i; j++) 
+            left = max(left, arr[j]); 
+
+        // Find the maximum element on its right 
+        int right = arr[i]; 
+        for (int j = i + 1; j < n; j++) 
+            right = max(right, arr[j]); 
+
+        // Update the maximum water 
+        res = res + (min(left, right) - arr[i]); 
+    } 
+
+    return res; 
+} 
+
+// Driver code 
+int main() 
+{ 
+    int arr[] = { 0, 1, 0, 2, 1, 0, 1, 3, 2, 1, 2, 1 }; 
+    int n = sizeof(arr) / sizeof(arr[0]); 
+
+    cout << maxWater(arr, n); 
+
+    return 0; 
+}