世界上最好的题解

    #include <iostream>
    #include <algorithm>
    #include <cstring>
    #define int long long

    using namespace std;
    const int N = 5e6 + 10;
    int a[N];
    inline void solve()
    {
        int t;
        cin >> t;
        int num = 1;
        while (t -- )
        {  
            
            int nx;
            cin >> nx;
            for (int i = 1 ; i <= nx ; i ++ )
            {
                char temp;
                cin >> temp;
                a[i] = temp - '0';
                a[i] = a[i - 1] + a[i];
            }

            int ans = 0;
            int n;
            if (nx & 1) n = nx + 1;
            else n = nx;
            for (int i = 1 ; i <= n / 2 ; i ++ )
            {
                int temp = a[i + n / 2 - 1] - a[i - 1];
                ans = max(ans , temp);

                // cout << temp << endl;
            }
            // if (num == 3) cout << ans << endl;
            for (int i = nx ; i >= nx / 2 ; i -- )
            {
                int temp = a[i] - a[i - nx / 2];
                ans = max(ans , temp);

                // cout << temp << endl;
            }


            cout << "Case #" << num << ": " << ans << endl;
            num ++;
        }
        return ;
    }

    signed main()
    {
        ios::sync_with_stdio(false) , cin.tie(0) , cout.tie(0);
        solve();
        return 0;
    }