I encountered this problem named MEX problem in **Mercari, Inc / Software Engineer (New Graduate Position) Hiring Test 2022** and was not able to think of a possible approach to solve this problem\n\nplease shed some light on how to approach such type of questions\n\n![image](https://assets.leetcode.com/users/images/efc57c97-106f-4e12-a2fe-8415f101d937_1645815187.9360535.jpeg)\n\nedit:\n\ni am uploading other questions for your reference (P.S i was able to solve these)\n\nquestion 2 (based on bit manipulation):\n\n\n![image](https://assets.leetcode.com/users/images/ae75aab1-2872-49ce-8fc7-87ac4c27148c_1652559164.3460577.jpeg)\n\n![image](https://assets.leetcode.com/users/images/4e891ce2-9e8c-42fb-8511-b5ce451a705a_1652559164.2308998.jpeg)\n\nquestion 3 (based on simple anagram):\n\n\n![image](https://assets.leetcode.com/users/images/d6b1a526-97a4-4240-be08-f6e6e6c743b4_1652559164.3348167.jpeg)\n\n![image](https://assets.leetcode.com/users/images/85292966-bb73-4a80-bb51-841f01525089_1652559164.1391282.jpeg)\n\n

I encountered this problem named MEX problem in Mercari, Inc / Software Engineer (New Graduate Position) Hiring Test 2022 and was not able to think of a possibl