using two sets

a = int(input()) datas = list(map(int,input().split())) seta = set() setb = set() for each in datas: if each not in seta: seta.add(each) setb.add(each) else: #print(each) setb.discard(each)

print(setb.pop())

i = int(input())

list_1 = list(map(int,input().split()))

list_1.sort()

x = 0

while x < len(list_1) - 1:

if list_1[x] != list_1[x + 1]:

    print(list_1[x])
    break
else:

    x += i  # Skip over group

else:

# If captain is at the end
print(list_1[-1])

I tried using set since it is from the sets section. Time is exceeding limit, anyone who can optimize this. N=int(input()) m=list(map(int, input().split())) n=set(m) l=[] for i in n: count=0 for j in m: if i==j: count +=1 l.append([i,count])

for i in l: if i[1]==1: print(i[0])

Here is HackerRank The Captain's Room in Python solution - https://programmingoneonone.com/hackerrank-the-captains-room-solution-in-python.html

from collections import Counter

k = int(input())

room_list = list(map(int , input().split()))

room_count = Counter(room_list)

for room_list , room_members in room_count.items():

    if room_members == 1:
    print(room_list)