Ardent Butterfly Collector (Editorial)

Store the species numbers of butterflies in a set $s$. Then, to determine whether a butterfly of species $x$ is in Andrey Sergeevich's collection, simply check whether $x$ belongs to the set $s$.

Algorithm implementation

Store all butterfly species numbers from the collection in the set $s$.

set<int> s;

Read the input data.

scanf("%d", &n);
for (i = 0; i < n; i++)
{
  scanf("%d", &x);
  s.insert(x);
}

Process $m$ queries.

scanf("%d", &m);
for (i = 0; i < m; i++)
{

Check whether a butterfly of species $x$ is in the collection. The answer is "YES" if the number $x$ is present in the set $s$.

  scanf("%d", &x);
  if (s.find(x) != s.end()) puts("YES");
  else puts("NO");
}

Python implementation

Read the input data.

n = int(input())
lst = list(map(int,input().split()))
m = int(input())
q = list(map(int,input().split()))

Store all butterfly species numbers from the collection in the set $s$.

s = set(lst)

Process $m$ queries.

for x in q:

Check whether a butterfly of species $x$ is in the collection. The answer is "YES" if the number $x$ is present in the set $s$.

  if x in s:
    print("YES")
  else:
    print("NO")