TrappingRain.cpp

// 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; 
}