牛客网多校第五场 inv （思惟+逆序）

连接：https://www.nowcoder.com/acm/contest/143/D 来源：牛客网  c++ Kanade has an even number n and a permutation b of all of the even numbers in [1,n]数组 Let a denote an array [1,3,5....n-1] , now you need to f

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