贴上学习FFT和NTT的资料，以后再补题吧

http://blog.miskcoo.com/2015/04/polynomial-multiplication-and-fast-fourier-transform#i-15

http://blog.csdn.net/acdreamers/article/details/39005227

http://blog.csdn.net/acdreamers/article/details/39026505

FFT及NTT学习