Sazzad's problem in O(logn)

#include <bits/stdc++.h>
using namespace std;

int main() {
    vector<int> arr = {1, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 5, 8, 9};

    int n;
    cin >> n;
    int indexOne = lower_bound(arr.begin(), arr.end(), n) - arr.begin();
    int indexTwo = upper_bound(arr.begin(), arr.end(), n) - arr.begin();
    int result = indexTwo - indexOne;
    cout << n << " occurs " <<  result << " time" << endl;

    return 0;
}