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# 04/19/2022 202. Happy Number

Method: this problem can be divided into 2 situations. First, After the operation required by the question, the number would become 1. Another case is the numbers would stuck in circle/loop. So we first write a getNumber method to get the sum of the square of each digit. Then we use HashSet to decide if the number next to add is in the set.

Time O(logn)

Space O(N)