摘要：$$a^2+b^2=c^2$$ $$F(\omega)=\mathcal{F}[f(t)]=\int_{ \infty}^\infty f(t)e^{ iwt}\,dt$$ $$\sum_{i=0}^n C_i^n =2^n$$ $$O(N\log N)$$ $$O (\sqrt{N^3})$$ $ 阅读全文