A_Brogramming_Contest.cpp

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

// Macros and constants
#define endl ("\n")
#define pi (3.141592653589)
#define int long long
#define float double
#define pb push_back
#define mp make_pair
#define ff first
#define ss second
#define all(c) c.begin(), c.end()
#define mini(a, b, c) min(c, min(a, b))
#define mini2(a, b, c, d) min(d, min(c, min(a, b))) 
#define rrep(i,s,n) for(int i=n-1;i>=s;i--)
#define rep(i,n) for(int i=0;i<n;i++)
#define fast ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
#define scin(str) getline(cin, str)

// Debugging Macros
#define debug(x) cerr << #x << " = " << x << endl
#define debug2(x, y) cerr << #x << " = " << x << ", " << #y << " = " << y << endl

// Aliases and Types
using vec = vector<int>;
using pii=pair<int,int>;
using mapi=map<int,int>;
using si=set<int>;

const int mod = 1e9+7;

// Global Constants
const int dx[4]{1, 0, -1, 0}, dy[4]{0, 1, 0, -1};  // for every grid problem!!
const int N=2e5+5;


void solve(){
    int n;
    cin >> n;
    string s;
    cin >> s;
    int cnt = 0;
    for(int i = n-1; i >= 0; i--) {
        if(s[i] == '0') {
            continue;
        }
        while(i >= 0 && s[i] == '1') {
            i--;
        }
        cnt++;
       
    }

    if(s[n-1] == '1') {
        cout << 2 * cnt - 1 << endl;
    } 
    else 
        cout << 2 * cnt << endl;
}


int32_t main(){
    fast

    int t = 1;
    cin >> t;
    while(t--){
        
        
        solve();


    }
    return 0;
}