codeforces/1788A.cpp at main · Nithin0306/codeforces · GitHub

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

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


        int total_number_of_twos = 0;
        int current_number_of_twos = 0;

        for (int i = 0; i < n; i++)
        {
            if (a[i] == 2)
                total_number_of_twos++;
        }

        int ans = -1;

        for (int i = 0; i < n; i++)
        {
            if (a[i] == 2)
                current_number_of_twos++;

            if ((current_number_of_twos) == (total_number_of_twos - current_number_of_twos))
            {
                ans = i + 1;
                break;
            }
        }

        cout << ans << endl;
    }
    return 0;
}