链接:https://www.nowcoder.com/acm/contest/147/H 来源:牛客网
Niuniu has learned prefix sum and he found an interesting about prefix sum.
Let’s consider (k1) arrays a[i] (0 < i < k) The index of a[i] starts from 1. a[i] is a…
前置知识
(1)毕达哥拉斯定理: sin 2 α cos 2 β 1 \sin^2\alpha\cos^2\beta1 sin2αcos2β1
(2)诱导公式: sin ( 2 k π α ) sin α , cos ( 2 k π α ) cos α , ( k ∈ Z )…