A

#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;

const int N = 5e4 + 10;

int T;
int n;
int a[N];

int main()
{
    cin >> T;
    while(T -- )
    {
        cin >> n;
        memset(a, 0, sizeof a);
        for(int i = 0; i < n; i ++ )
        {
            cin >> a[i];
        }

        long long nn = 1e9 + 10;
        for(long long i = 0, j = 1; j < n; i ++, j ++ )
        {
            long long t = max(a[i], a[j]);
            nn = min(nn, t);
        }
        cout << nn - 1 << endl;

    }

    return 0;
}

B

#include <iostream>
#include <algorithm>

using namespace std;

int main()
{
    int t;
    cin >> t;
    while (t--) 
    {
        int a, b;
        cin >> a >> b;

        for (int i = 0; i < 30; i++) 
        {
            if ((a & (1 << i)) != (b & (1 << i))) 
            {
                cout << (1ll << i) << "\n";
                break;
            }
        }
    }
}

C

#include <iostream>
#include <algorithm>
#include <cstring>
#include <vector>

using namespace std;

const int N = 1e9 + 10;

int gcd(int a, int b) 
{
    while (b != 0) 
    {
        int tmp = a % b;
        a = b;
        b = tmp;
    }
    return a;
}
int lcm(int a, int b) 
{
    return a * b / gcd(a, b);
}

int main()
{
    int t;
    cin >> t;
    while(t -- )
    {
        int n;
        vector <int> a(n);
        cin >> n;
        for(int i = 0; i < n; i ++ )
        {
            cin >> a[i];
        }

        int zz = 1;
        for(int i = 0; i < n; i ++ )
        {
            zz = lcm(zz, a[i]);
        }

        int sum = 0;
        for(int i = 0; i < n; i ++ )
        {
            sum += (zz / a[i]);
        }

        if (sum < zz) 
        {
            for (int i = 0; i < n; i++) 
            {
                cout << zz / a[i] << " ";
            }
            cout << endl;
        } 
        else 
        {
            cout << -1 << "\n";
        }
    }

    return 0;
}