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I do not understand the logic. When do we stop? How dow we know it's gonna be an infinite loop?

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#1

I do not understand the logic. When do we stop? How dow we know it’s gonna be an infinite loop?

#2

We use Fast and Slow pointers to detect the cycle (infinite loop). The algorithm is based on the Floyd’s cycle-finding algorithm (also called the “tortoise and the hare algorithm”). If the Fast pointer reaches 1, we come to know that the number is a Happy number. Otherwise, the Fast pointer would reach the Slow pointer which depicts that a cycle is detected and the number is not a Happy number.

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