Bit string

input/code.cpp: In function 'int main()':
input/code.cpp:22:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%s", s + 1);
     ~~~~~^~~~~~~~~~~~~

#include <bits/stdc++.h>

using namespace std;

//#define FILE_IO

typedef long long LL;

const int NMAX = 5e5;

int N;
int fq[2];
char s[NMAX + 5];

int main()
{
    #ifdef FILE_IO
    freopen("1.in", "r", stdin);
    //freopen(".out", "w", stdout);
    #endif

    scanf("%s", s + 1);
    N = strlen(s + 1);

    fq[0] = 1;
    int sum = 0;
    for(int i = 1; i <= N; i++)
    {
        sum ^= (s[i] - '0');
        fq[sum]++;
    }

    LL ans = 1LL * fq[0] * (fq[0] - 1) / 2 + 1LL * fq[1] * (fq[1] - 1) / 2;
    cout << ans << '\n';

    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