Given an integer array nums, every element appears exactly $3$ times except for $1$ element that appears once and $1$ element that appears twice.

Return an array containing the element that appears once followed by the element that appears twice.

Constraints:

• $3 \leq$ nums.length $\leq 10^5$

• $-2^{31} \leq$ nums[i] $\leq 2^{31} - 1$

• nums.length is a multiple of $3$

• Exactly $1$ element appears once, $1$ element appears twice, and all other elements appear $3$ times

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