In mathematics you don't understand things, you just get used to them.

学了五年 KMP拜谢 oi-wiki。字符串下标从 $0$ 开始,$s_{[l, r]}$ 闭区间子串,定义 $\displaystyle \pi_i = \max_{j \in [0, i]}...

区间加法可以差分的原因是 $\Delta_i = \Delta_{i-1}$,所以令 $\textit{d}_i = \Delta_i-\Delta_{i-1}$,对于一个一般点的 $\Delt...

Quack 知道好多东西,把它们都做成 ppt。inv_gcd 还可以用递推矩阵算。void exgcd(int a, int b){ r[0] = a, r[1] = b; int i...