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Photoshoot 题目描述 Farmer John is lining up his N cows (2≤N≤103), numbered 1…N, for a photoshoot. FJ initially planned for the i-th cow from the left to be the cow numbered ai, and wrote down the permuta...

Sum Equals Xor 题目描述 You are given a positive integer L in base two. How many pairs of non-negative integers (a,b) satisfy the following conditions? ·a+b≤L ·a+b=a XOR b Since there can be extremely man...

取石子 **题目描述** n+e最近在研究取⽯⼦游戏。 有n堆⽯⼦，第i堆⽯⼦有ai个，最多取m堆⽯⼦（保证m≤n），请问在要求总⽯⼦数不超过k的情况下最多能取多少⽯⼦。 **输入** 第⼀⾏输⼊3个数字n,m,k，意义见上。 第⼆⾏n个数字，依次表示ai。 **输出** 输出⼀个数字，表示你的答案。 **样例输入 ** 4 3 5 1 1 2 3 **样例输出** 5 **提示** 取第1、2...

题目描述 A sequence a1,a2,…,an is said to be //// when the following conditions are satisfied: For each i=1,2,…,n−2, ai=ai+2. Exactly two different numbers appear in the sequence. You are given a sequence...