Python solution for trapping rain water in DSA 450

Author: dsrao711

DSA 450 GFG/TrapRainWater.py

@@ -0,0 +1,48 @@
+# Problem : https://practice.geeksforgeeks.org/problems/trapping-rain-water-1587115621/1
+
+class Solution:
+    def trappingWater(self, arr,n):
+        #Code here
+        left = [0]*n
+        right = [0]*n
+
+        left[0] = arr[0]
+        right[n-1] = arr[n-1]
+        trap_sum = 0
+        
+        for i in range (1 , n):
+            left[i] = max(left[i-1] , arr[i])
+        for i in range(n-2 , -1 , -1):
+            right[i] = max(arr[i] , right[i+1])
+        for i in range (0 , n):
+            trap_sum += min(left[i] , right[i]) - arr[i]
+                
+        return trap_sum
+#{ 
+#  Driver Code Starts
+#Initial Template for Python 3
+
+import math
+
+
+
+def main():
+        T=int(input())
+        while(T>0):
+            
+            n=int(input())
+            
+            arr=[int(x) for x in input().strip().split()]
+            obj = Solution()
+            print(obj.trappingWater(arr,n))
+            
+            
+            T-=1
+
+
+if __name__ == "__main__":
+    main()
+
+
+
+# } Driver Code Ends