1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
#include <bits/stdc++.h>
#define REP(i,n) for (int _n=(n), i=0;i<_n;++i)
#define FOR(i,a,b) for (int i=(a),_b=(b);i<=_b;++i)
#define FORD(i,a,b) for (int i=(a),_b=(b);i>=_b;--i)
#define TRACE(x) std::cerr << "TRACE(" #x ")" << std::endl;
#define DEBUG(x) std::cerr << #x << " = " << (x) << std::endl;

void init_io() {
  std::cin.tie(nullptr);
  std::ios::sync_with_stdio(false);
}

int solve_case() {
  int n;
  std::cin >> n;
  std::vector<int> count(2*n + 1, 0);
  bool leftmost = true;
  int len = 0;
  REP(i, n) {
    char c;
    std::cin >> c;
    if (c=='0') {
      ++len;
    } else if (c=='1') {
      if (leftmost) {
        count[2 * len] += 1;
      } else {
        count[len] += 2;
      }
      len = 0;
      leftmost = false;
    } else {
      assert(false);
    }
  }
  if (leftmost) {
    // no virus
    return 0;
  }
  count[2*len] += 1;

  int saved = 0;
  int water = 0;
  FORD(len, 2*n, 1) {
    REP(i, count[len]) {
      if (len <= water) goto done;
      saved += len - water;
      water += 2;
    }
  }
done:
  return n - (saved + 1) / 2;
}

int main() {
  init_io();

  int ntc;
  std::cin >> ntc;
  REP(tc, ntc) {
    int res = solve_case();
    std::cout << res << '\n';
  }
}