sum of numbers in a given range

#include<iostream>
#include<vector>
#include<bits/stdc++.h>
#include<cstdio>
using namespace std;
int main()
{
int num1 = 73;
int num2 = 89;
int sum = 0;
for (int i = num1; i <= num2; i++)
sum = sum + i;
cout << sum;
return 0;
}
// Time complexity : O(N)
// Space complexity : O(1)