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Any fast solution?

2023-02-15 00:37:25 By 837951602

$$\text{Decide if the following equation has solution:}$$ $$A_{m \times n} \cdot B_{n \times k} = X_{m \times k}$$ $$M \preceq A \preceq N, P \preceq B \preceq Q$$ $$\text{Where } F\preceq G \text{ means every element in }F\text{ is }$$ $$\text{smaller than the value on same position of }G$$ $$ X, M, N, P, Q \text{ are known}$$

EDIT@23/02/15 13:27: 用机械结构求解会卡住吗?

FFT利用复数减少一半点

2020-04-16 12:52:04 By 837951602

我看#34的榜,double做法都是 $$x_i=a_{2i}+ia_{2i+1}\\Z_i=X_iY_i-\frac 14\left(1+w_N^i\right)\left(X_i-\overline{X_{N-i}}\right)\left(Y_i-\overline{Y_{N-i}}\right)$$ 而不是 $$x_i=a_iu^i+a_{i+n}u^{i+n}\\Z_i=X_iY_i$$ 这两个方法,哪个更显然?哪个效率高?(我提交改了输出挂还去了swap过程,但另一种方法也能做)

LaTeX怎么画二叉树?

2020-04-09 21:15:08 By 837951602

$$\begin{matrix}&&&O\\&&/&&\\\&O&&&&O\\~/&&\backslash~&&~/&&\backslash~\\O~&&~O&&~O&&~O \end{matrix}$$ 这样如果层数再多,倾斜度就不够了……

#69 Hack

2020-04-07 19:53:44 By 837951602
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