Bittijono

input/code.cpp: In function 'int main()':
input/code.cpp:17:6: warning: unused variable 'z' [-Wunused-variable]
   ll z = 0, ones = 0;
      ^

#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i=a; i<(b); i++)
#define IO ios_base::sync_with_stdio(0); cin.tie(0);

typedef long long ll;
using namespace std;

string s;

int main() {
  IO;
  string s; cin>>s;
  int n = s.size();
  
  ll ans = 0;
  ll even_zero = 0, odd_zero = 0;
  ll z = 0, ones = 0;
  
  FOR(i,1,n+1) {
    
    ll add = 0;
    if (s[i-1] == '0') {
      if (ones % 2 == 1) add = odd_zero + ones/2;
      else add = even_zero + ones/2;
      add++;
      
      if (ones % 2 == 0) even_zero++;
      else odd_zero++;
    } else {
      ones++;
      if (ones % 2 == 0) add = even_zero + ones/2;
      else add = odd_zero + ones/2;
    }
    
    //cout<<"Adding "<<add<<" at "<<i<<"\n";
    ans += add;
  }
  
  cout<<ans<<"\n";
}

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