Sum of ones

#include <bits/stdc++.h>

#define int long long

void init_code() {
    std::ios_base::sync_with_stdio(0);
    std::cin.tie(0);
    #ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif
}

using namespace std;

void solve() {
    int n;
    cin >> n;

    n += 1;
    
    int res = 0;
    int step = 2;
    
    bool flag = true;
    
    while (flag) {
        int tmp = 0;

        tmp += (n / step) * (step / 2);
        //cout << tmp << '\n';
        
        int x = (n % step);
        int y = (step / 2);
            
        if (x > y) {
            tmp += x % y;
        }
        //cout << x << ' ' << y << ' ' << x % y << '\n';
        //cout << step << ' ' << tmp << '\n';
        //cout << '\n';
        if (tmp <= 0 || step >= n) {
            flag = false;
        }

        res += tmp;
        step = step * 2;
    }

    cout << res << '\n';
}


signed main() {
    init_code();
    int t = 1;
    //cin >> t;
    while (t--) {
        solve();
    }
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED