| Codeforces Round 1080 (Div. 3) |
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| Finished |
Consider the following cube $$$D$$$ where numbers $$$x$$$ and $$$7-x$$$ lie on opposite sides:
Image generated by Nano Banana Pro. A sequence $$$b$$$ of integers from $$$1$$$ to $$$6$$$ is called a dice roll sequence if it satisfies the following condition:
For example, $$$[1,4,2]$$$ is a dice roll sequence, while $$$[3,4,6,3]$$$ is not because $$$3$$$ and $$$4$$$ are not on adjacent sides of the dice. Additionally, $$$[2,2,4]$$$ is not a dice roll sequence because $$$2$$$ and $$$2$$$ are on the same (not adjacent) side of the dice.
Given a sequence $$$a$$$ of $$$n$$$ integers from $$$1$$$ to $$$6$$$, you can perform the following operation any number of times (possibly zero).
Please determine the minimum number of operations required to make $$$a$$$ a dice roll sequence.
$$$^{\text{∗}}$$$Two sides of the cube $$$S$$$ and $$$T$$$ are called adjacent if they share exactly one edge of the cube. Do note that this condition implies $$$S \neq T$$$ as well.
Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 10^4$$$). The description of the test cases follows.
The first line of each test case contains a single integer $$$n$$$ ($$$1 \le n \le 3 \cdot 10^5$$$).
The second line of each test case contains $$$n$$$ integers $$$a_1,a_2,\ldots,a_n$$$ ($$$1 \le a_i \le 6$$$).
It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$3 \cdot 10^5$$$.
For each test case, output the minimum number of operations required to make $$$a$$$ a dice roll sequence.
331 4 243 4 6 3106 1 4 3 1 3 2 5 4 4
014
For the first test case, the sequence $$$a$$$ is $$$[1,4,2]$$$. As this is already a dice roll sequence, the answer is $$$0$$$.
For the second test case, the sequence $$$a$$$ is $$$[3,4,6,3]$$$.
Changing exactly one element, you can get $$$[3,\color{red}{5},6,3]$$$, which is a dice roll sequence.
For the third test case, the sequence $$$a$$$ is $$$[6,1,4,3,1,3,2,5,4,4]$$$.
Changing exactly $$$4$$$ elements, you can get $$$[\color{red}{5},1,4,\color{red}{2},1,3,2,\color{red}{1},\color{red}{5},4]$$$, which is a dice roll sequence.
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