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easy· math-geometry Mock interview

Happy Number

A number is happy if repeatedly replacing it by the sum of the squares of its digits eventually reaches 1. If it loops forever without reaching 1, it is not happy. Given `n`, return true if it is happy.

Examples

in: n = 19

out: true

1+81=82, 64+4=68, 36+64=100, 1=1

in: n = 2

out: false

enters a cycle

Constraints

1 <= n <= 2^31 - 1

Hints

target: O(log n) per step⌘↩ run · ⇧⌘↩ submit