The hallmark of the Cooley-Tukey algorithm for Fast Fourier Transform is the butterfly network, which helps reduce O(N^2) computations to O(N*log*N). Butterflies are very special graphs entangled in routing [Arora], switching [Chung], shuffling [Yang], and mixing [Czumaj].

# 2-butterfly derangement

**10**
*Saturday*
Dec 2016

Posted Algorithms, Java, Mathematics, Permutations, Switching networks

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