Sum of ones

#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>


uint64_t ones_in(uint64_t n){
    if (n == 0)
        return 0;
    return n%2 + ones_in(n/2);
}

uint64_t ones_upto(uint64_t n){
    if (n == 1){
        return 0;
    }
    if (n%2 == 1){
        return ones_upto(n+1) - ones_in(n);
    } else {
        return n/2 + 2 * ones_upto(n/2);
    }
}


int main() {
    uint64_t n = 0;
    if (scanf("%ld", &n) == 0)
        return EXIT_FAILURE;

    // main algo

    printf("%ld\n", ones_upto(n + 1));

    return EXIT_SUCCESS;
}

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