题解 | 预知

#include <iostream>

#define LENGTH 110000
#define ll long long
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define MIN(a, b) ((a) < (b) ? (a) : (b))

using namespace std;


int main()
{
    int T;
    cin >> T;
    while (T--)
    {
        int n;
        cin >> n;
        int max = 0;
        ll sum = 0;
        for (int i = 0; i < n; i++) {
            int temp;
            cin >> temp;
            if (temp > max) {
                max = temp;
            }
            sum += temp;
        }
        if (n == 1) {
            cout << -1 << endl;
        } else if(max == 1) {
            cout << 0 << endl;
        } else {
            cout << MIN(sum - n, max) << endl;
        }
    }
    
    return 0;
}