ACLPC F
from AtCoder Library Practice Contest
ACLPC_F
F - Convolution
https://gyazo.com/dde1796c658447207ea2ef7a288c65a8
A naive convolution would be O(NM)
Applying the butterfly operation used in FFT, we obtain O(N logM)
https://www.onosokki.co.jp/HP-WK/eMM_back/emm140.pdf
I heard that NTT is also an option.
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