I was solving this [problem](https://codeforces.net/contest/1252/problem/K) and was getting TLE (3s) when using `vector<vector<ll>>` as my 2x2 matrix, then I converted it to `array<ll,4>` and I passed in 500 ms. Why is it so much faster?↵
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Update: [2D vector TLE code](https://www.ideone.com/4rcI8i), [array AC code](https://www.ideone.com/Vucvnt)↵
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Some notes: I wasn't sure why I was TLE so at first I tried using int instead of long long. I also stopped maintaining 2 versions of the matrices per node and did the flip transform mentioned in the editorial. Both of these optimizations didn't work, so I then tried converting my 2d vector to 1d array. I remember that trick working on some other matrix problem on CF that I solved from long time ago, but I can't remember which one it is.
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Update: [2D vector TLE code](https://www.ideone.com/4rcI8i), [array AC code](https://www.ideone.com/Vucvnt)↵
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Some notes: I wasn't sure why I was TLE so at first I tried using int instead of long long. I also stopped maintaining 2 versions of the matrices per node and did the flip transform mentioned in the editorial. Both of these optimizations didn't work, so I then tried converting my 2d vector to 1d array. I remember that trick working on some other matrix problem on CF that I solved from long time ago, but I can't remember which one it is.
