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
// {{{
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define FOR(i, b, e) for (int i = (b); i <= (e); i++)
#define FORD(i, b, e) for (int i = (e); i >= (b); i--)
#define MP make_pair
#define FS first
#define ND second
#define PB push_back
#define ALL(x) x.begin(), x.end()

using namespace std;

using LL = long long;
using LD = long double;
using PII = pair<int,int>;
using PLL = pair<LL,LL>;
using PLD = pair<LD,LD>;
using VI = vector<int>;
using VLL = vector<LL>;
using VLD = vector<LD>;
using VB = vector<bool>;
using VS = vector<string>;
template<class T>
using V = vector<T>;
template<class T1, class T2>
using P = pair<T1,T2>;
template<class T,class Comp=greater<T>>
using PQ = priority_queue<T,V<T>,Comp>;

template<class T>
int sz(const T& a) { return (int)a.size(); }
template<class T>
void amin(T& a, T b) { a = min(a, b); }
template<class T>
void amax(T& a, T b) { a = max(a, b); }

/*
const size_t rseed =
  std::chrono::high_resolution_clock::now().time_since_epoch().count();
mt19937 rnd(rseed);
template<class T> T randint(T lo, T hi)
{
  return uniform_int_distribution<T>{lo,hi}(rnd);
}
*/

/* find_by_order(k) - k'th largest counting from 0;
   order_of_key(k) - number of items strictly smaller than k;
   join(other), split(k, other) - all keys in other greater than in *(this). */
template<class K,class V,class Comp=less<K>>
using ordered_map = __gnu_pbds::tree<K,V,Comp,
      __gnu_pbds::rb_tree_tag,__gnu_pbds::tree_order_statistics_node_update>;
template<class T,class Comp=less<T>>
using ordered_set = ordered_map<T,__gnu_pbds::null_type,Comp>;

const int inf = 1e9 + 1;
const LL infl = 1e18 + 1;

void solve();
// }}}

int main()
{
  int t = 1;
  scanf("%d", &t);
  FOR(i, 1, t) {
    // printf("Case #%d: ", i);
    solve();
  }
}

const int N = 1e5;
int n;
char s[N + 2];
VI a;

int f(int i, int x, int y, int t)
{
  if (i == sz(a)) {
    if (x - t > 0) {
      int best = x - t + f(i, y, 0, t + 1);
      return best;
    }
    else {
      return 0;
    }
  }
  else {
    int best = -1;
    if (x - t > 0) {
      amax(best, x - t + f(i, y, 0, t + 1)); // t - i += 1
    }

    int z = a[i] - 2 * t;
    if (z == 2 || z == 1) {
      amax(best, 1 + f(i + 1, x, y, t + 1)); // t - i += 0
    }
    else if (z > 2) {
      amax(best, z - 1 + f(i + 1, x, y, t + 2)); // t - i += 1
    }
    else {
      amax(best, f(sz(a), x, y, t)); // fall
    }

    return best;
  }
}

void solve()
{
  a.clear();

  scanf("%d %s", &n, &s[1]);

  int k = 0, x = 0, y = 0;
  bool b = true;
  FOR(i, 1, n) {
    if (s[i] == '1') {
      if (k > 0) {
        if (b) x = k;
        else a.PB(k);
      }
      b = false;
      k = 0;
    }
    else {
      k++;
    }
  }
  if (k > 0) {
    if (x == 0) x = k;
    else {
      y = k;
      if (x < y) swap(x, y);
    }
  }

  if (b) {
    puts("0");
    return;
  }

  sort(ALL(a));
  reverse(ALL(a));

  /*
  fprintf(stderr, "> ");
  FOR(i, 0, sz(a) - 1) fprintf(stderr, "%d ", a[i]);
  fprintf(stderr, "\n");
  */

  printf("%d\n", n - f(0, x, y, 0));
}