| Codeforces Round 1124 (Div. 2) |
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| Finished |
Kia and Kio spent the summer at the port of Mehragan, where $$$n$$$ lighthouses stand on the cliffs facing the dark sea.
The lighthouses of Mehragan do not give light. Every night a number is written in fire on each of them, and the sailors read their way from those numbers.
The law of the lighthouses is this: if a lighthouse shows $$$x$$$ tonight, then tomorrow night it shows the sum of the squares of the decimal digits of $$$x$$$.
For example, a lighthouse showing $$$23$$$ will show $$$2^2+3^2=13$$$ tomorrow, then $$$1^2+3^2=10$$$, and then $$$1$$$.
On night $$$0$$$ of the season, lighthouse $$$i$$$ shows the number $$$a_i$$$. From that night on, the law is applied once every night, forever.
Kio calls two lighthouses $$$i$$$ and $$$j$$$ in tune if there exists a night after which, forever, both of them show exactly the same number on every single night.
Kia asks: how many pairs $$$(i, j)$$$ with $$$i \lt j$$$ are in tune?
Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 1000$$$). The description of the test cases follows.
Each test case consists of two lines.
The first line of each test case contains a single integer $$$n$$$ ($$$1 \le n \le 1000$$$) — the number of lighthouses.
The second line contains $$$n$$$ integers $$$a_1, a_2, \ldots, a_n$$$ ($$$1 \le a_i \le 10^9$$$) — the number shown by each lighthouse on night $$$0$$$.
It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$1000$$$.
For each test case, print a single integer — the number of pairs $$$(i, j)$$$ with $$$i \lt j$$$ such that lighthouses $$$i$$$ and $$$j$$$ are in tune.
457 4 16 4 241 7 10 10034 16 3732 20 4
1601
In the first test case:
So the only pair in tune is $$$(2, 4)$$$, and the answer is $$$1$$$.
In the second test case, every lighthouse sooner or later reaches $$$1$$$ and stays there, so all of them are pairwise in tune, which gives $$$6$$$ pairs.
In the fourth test case, on night $$$1$$$, lighthouse $$$2$$$ shows $$$2^2+0^2 = 4$$$, and lighthouse $$$1$$$ shows $$$2^2 = 4$$$. From night $$$1$$$ on, they are identical forever. Lighthouse $$$3$$$ starts at $$$4$$$, so it is one night ahead of both of them and is in tune with neither.
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