CodeForces 702B Powers of Two【二分/lower_bound找多少个数/给出一个数组 求出ai + aj等于2的幂的数对个数】...
B. Powers of TwoYou are givennintegersa1, a2, ..., an. Find the number of pairs of indexesi, j(i < j) thatai + ajis a power of2(i. e. some integerxexists so thatai + aj = 2x)....
