链接:https://ac.nowcoder.com/acm/contest/881/H 来源:牛客网 题目描述 Bobo has a set A of n integers a1,a2,…,ana_1, a_2, \dots, a_na1,a2,…,an. He wants to know the sum of sizes for all subsets of A whose xor sum is zero modulo (109+7)(10^9+7)(109+7). Formally, find (∑S⊆A,⊕x∈Sx=0∣S∣) mod (109+7)\left(\sum_...