9.1arc108e当已经选了\(a_l,a_r\)时，\((l,r)\)与外面无关。区间dp，\(dp_{l,r}=\frac{\sum_{k=l,a_l<a_k<a_r}^rdp_{l,k}+dp_{k,r}}{num_{l,r}}+1\)。维护\(num_{l,r},\sumdp_{l,k},\sumdp_{k,r}\)转移。9.2P5188模拟赛T2。容斥强行不选\(s\)这些材料，矩阵快速幂。