Bit string

/* Murad Eynizade */

#include <bits/stdc++.h>
#define intt long long
#define FAST_READ ios_base::sync_with_stdio(0);cin.tie(0);
#define SIZE 1000001
#define INF INT_MAX
#define F first
#define S second
#define in(a) scanf("%d",&a);
#define outn(a) printf("%d\n",&a);
#define outs(a) printf("%d ",&a);


using namespace std;

int len;

intt ans , cnt[2] , co;

string s;

int main()
{
    FAST_READ;
    cin>>s;
    len = s.length();
    for (int i = 0;i<len;i++) {
        if (s[i] == '1')co++;
        if (co % 2 == 1) ans += cnt[1];
        else ans += cnt[0] + 1;
        cnt[co % 2]++;
    }
    cout<<ans<<endl;
    return 0;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 1

Verdict: ACCEPTED

Test 7

Group: 1

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED

Test 14

Group: 2

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED

Test 16

Group: 3

Verdict: ACCEPTED

Test 17

Group: 3

Verdict: ACCEPTED

Test 18

Group: 3

Verdict: ACCEPTED

Test 19

Group: 3

Verdict: ACCEPTED

Test 20

Group: 3

Verdict: ACCEPTED

Test 21

Group: 3

Verdict: ACCEPTED