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
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
#include <bits/stdc++.h> 

typedef long long int lli;

using namespace std;

#define MAX4 10010
#define MAX5 100010
#define MAX6 1000010

template <typename T >
void dbg(T last)
{
  cout << last << "\n";
}

template <typename T, typename ...args>
void dbg(T current, args ...next)
{
  cout << current << ' ';
  dbg(next...);
}

//-----------------------------------------------------------------------------------------------//
char tab[MAX6];
void solve()
{
  int n;
  cin >> n;
  for(int i=0;i<n;i++)
  {
    cin >> tab[i];
  }

  int first = 0;
  int s,e;

  for (int i=0;i<n;i++)
  {
    if (tab[i] == '0')
    {
      first++;
    }
    else
    {
      s=i;
      break;
    }
  }

  if (first == n)
  {
    cout << "0\n";
    return;
  }

  int last = 0;

  for (int i=n-1;i>=0;i--)
  {
    if (tab[i] == '0')
    {
      last++;
    }
    else
    {
      e=i;
      break;
    }
  }

  int cnt =0;

  vector<int> v;

  for (s;s<=e;s++)
  {
    if (tab[s] == '0')
    {
      cnt++;

      if (s == e)
      {
        v.push_back(cnt);
      }
    }
    else
    {
      v.push_back(cnt);
      cnt = 0;
    }
  }

  sort(v.begin(), v.end(), greater<int>());

  int sum = 0;
  cnt = 0;
  int turn = 0;

  while (true)
  {
    int x;
    if (cnt < v.size())
    {
      x = v[cnt];
    }
    else
    {
      x = 0;
    }

    x -= 2*turn;

    if (x <= 0 && last <= 0 && first <= 0)
    {
      break;
    }

    if ((x - 1> last && x - 1> first && x > last + first - 1) || (last <= 0 && first <= 0))
    {
      cnt++;
      sum += (x > 1 ? x - 1 : x);
      turn++;
      first -= 1;
      last -= 1;
    }
    else
    {
      if (last > first)
      {
        sum += last;
        last = 0;
      }
      else
      {
        sum += first;
        first = 0;
      }
    }

    first -= 1;
    last -= 1;
    turn++;
  }

  cout << n - sum << "\n";
}

int main()
{
  std::ios::sync_with_stdio(false);

  int n;

  cin >> n;

  while (n--)
  {
    solve();
  }

  return 0;
}