Sum of ones

#include <algorithm>
#include <cmath>
#include <iostream>
#include <queue>
#include <vector>

using namespace std;

int GetLeftMostSetBit(int n) {
    int pos = 0;

    while (n > 0) {
        pos++;
        n >>= 1;
    }

    return pos;
}

int countSetBits(int n) {
    int leftMostSetBitInd = GetLeftMostSetBit(n);

    int totalRep, mod;
    int nearestPow;
    int totalSetBitCount = 0;
    int addRemaining = 0;

    int curr = 0;

    for (int i = 1; i <= leftMostSetBitInd; ++i) {
        nearestPow = pow(2, i);
        if (nearestPow > n) {
            int lastPow = pow(2, i - 1);
            mod = n % lastPow;
            totalSetBitCount += mod + 1;
        } else {
            if (i == 1 && n % 2 == 1) {
                totalRep = (n + 1) / nearestPow;
                mod = nearestPow % 2;
                addRemaining = 0;
            } else {
                totalRep = n / nearestPow;
                mod = n % nearestPow;

                if (mod >= (nearestPow / 2)) {
                    addRemaining = mod - (nearestPow / 2) + 1;
                } else {
                    addRemaining = 0;
                }
            }

            curr = totalRep * (nearestPow / 2) + addRemaining;
            totalSetBitCount += curr;
        }
    }

    return totalSetBitCount;
}

int main() {
    int x;
    cin >> x;
    cout << countSetBits(x) << endl;
    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: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: WRONG ANSWER

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: WRONG ANSWER