Median of sorted array error

#1

i have used vector , it is giving me error , dont know why ? please help

#2 
 ll n;
 cin >> n;
 vector<ll>v1, v2;
 vector<ll> v(2 * n);

 f(i, 0, n) {
      ll x;
      cin >> x;
      v1.pb(x);
 }

 f(i, 0, n) {
      ll x;
      cin >> x;
      v2.pb(x);
 }
 merge(v1.begin(), v1.end(), v2.begin(), v2.end(), v.begin());
 cout << (v[n] + v[n - 1]) / 2;
#3

thanks for debugging , but please why declaring vector without size solves this problem ???

#4

because your vector size is initially is n and you push another n elements in it… so size becomes 2n

#5

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