Equilibrium point in an array

// C++ program to find equilibrium 
// index of an array 
#include <bits/stdc++.h> 
using namespace std; 

int equilibrium(int arr[], int n) 
{ 
	int sum = 0; // initialize sum of whole array 
	int leftsum = 0; // initialize leftsum 

	/* Find sum of the whole array */
	for (int i = 0; i < n; ++i) 
		sum += arr[i]; 

	for (int i = 0; i < n; ++i) 
	{ 
		sum -= arr[i]; // sum is now right sum for index i 

		if (leftsum == sum) 
			return i; 

		leftsum += arr[i]; 
	} 

	/* If no equilibrium index found, then return 0 */
	return -1; 
} 

// Driver code 
int main() 
{ 
	int arr[] = { -7, 1, 5, 2, -4, 3, 0 }; 
	int arr_size = sizeof(arr) / sizeof(arr[0]); 
	cout << "First equilibrium index is " << equilibrium(arr, arr_size); 
	return 0; 
} 

// This is code is contributed by rathbhupendra