qq_46173805的博客

E. Missing Numberssolution已知a1,a2,a3,a4,...,an−1,an,前缀和sum2[i]均为平方数，a_1,a_2,a_3,a_4,...,a_{n-1},a_n,前缀和sum^2[i]均为平方数，a1​,a2​,a3​,a4​,...,an−1​,an​,前缀和sum2[i]均为平方数，{sum[2k+1]=sum2[2k]+xsum[2k+2]=sum2[2k+1]+y\begin{cases}sum[2k+1]=\sqrt{sum^2[2k] + x}\\