easy Q that asks the missing numberclass Solution: # 0~n 까지인 배열/set/dict를 만들고, nums 에 for 돌리면서 없는지 찾기 def missingNumber(self, nums: List[int]) -> int: # for no in range(len(nums)+1): # if no not in nums: # return no n = len(nums) ex_res = (n*(n+1))//2 tmp = sum(nums) return ex_res-tmp At first attempt...came up with a common ans,..