Bittijono

#include<bits/stdc++.h>
using namespace std;

int main() {
  string s; cin >> s;
  int n = s.length();
  bool b[501010]; for(int i = 0; i < n; i++) {
    if(s[i] == '0') b[i] = 0;
    else b[i] = 1;
  }
  long p = 0;
  long pp = 0;
  long on = 0;
  long ze = 0;
  long cc = 0;
  long zep = 0;
  for(int i = 0; i < n; i++) {
    if(!b[i]) {
      zep++;
    }

    else {
      for(int i = zep; i >= 1; i--) {
	cc += i;
      }
      zep = 0;
    }
    if(i == n-1) {
      for(int i = 1; i <= zep; i++) {
	cc += i;
      }
    }
  }
  for(int i = 0; i < n; i++) {
    if(b[i]) {
      on++;
      if(on%2==0) {
	pp += ze+1;
	cc += p;
      }
      else {
	p += ze+1;
	cc += pp;
      }
      ze = 0;
    }
    else {
      if(on%2==0) cc += p;
      else cc += pp;
      ze++;
    }
  }
  cout << cc << endl;
}

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