Maximize the sum of selected numbers from an array to make it empty

// CPP program to Maximize the sum of selected
// numbers by deleting three consecutive numbers.
#include <bits/stdc++.h>
using namespace std;

// function to maximize the sum of selected numbers
int maximizeSum(int arr[], int n) {

	// Largest element in the array
	int mx = -1;
	for(int i = 0; i < n; i++)
	{
		mx = max(mx, arr[i]);
	}
	
	// An array to count the occurence of each element
	int freq[mx + 1];
	
	memset(freq, 0, sizeof(freq));
	
	for(int i = 0; i < n; i++)
	{
		freq[arr[i]]++;
	}
	
	// ans to store the result
	int ans = 0, i=mx;
	
	// Using the above mentioned approach
	while(i>0){
		
		// if occurence is greater than 0
		if(freq[i] > 0){
			// add it to ans
			ans += i;
			
			// decrease i-1th element by 1
			freq[i-1]--;
			
			// decrease ith element by 1
			freq[i]--;
		}else{
			// decrease i
			i--;
		}	
	}
	
	return ans;
}

// Driver code
int main()
{
int a[] = {1, 2, 3};
int n = sizeof(a) / sizeof(a[0]);
cout << maximizeSum(a, n);
return 0;
}