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
#include <bits/stdc++.h>

using namespace std;
#define pb push_back
#define st first
#define nd second
vector <pair <int, bool> > v;

int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int t, n, ost, ld, ans;
	string s;
	cin >> t;
	for(int j = 0; j < t; j++){
		cin >> n;
		cin >> s;
		ost = 0;
		for(int i = 0; i < n; i++){
			if(s[i] == '1'){
				if(ost == 0) v.pb({i*2, 1});
				else v.pb({i - ost, 0});
				ost = i+1;
			}
		}
		if(v.size()){
			v.pb({2*(n - ost), 1});
			sort(v.begin(), v.end(), greater<pair <int, bool> >());
			ld = 0;
			ans = 0;
			//for(int i = 0; i < (int)v.size(); i++) cout << v[i].st << " " << v[i].nd << "\n";
			for(int i = 0; i < (int)v.size(); i++){
				if(v[i].nd) {
					v[i].st /= 2;
					v[i].st -= ld;
					if(v[i].st > 0){
						ans += v[i].st;
						ld++;
					}
				}
				else{
					v[i].st -= 2 * ld;
					if(v[i].st > 0) {
						ans += max(v[i].st - 1, 1);
						ld += 2;
					}
				}
			}
			cout << n - ans << "\n";
		}
		else cout << 0 << "\n";
		v.clear();
	}
	
	return 0;
}