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B. Emordnilap 原题链接 A permutation of length n is an array consisting of n distinct integers from 1 to n in arbitrary order. For example, [2,3,1,5,4] is 阅读全文
摘要：
A. Everybody Likes Good Arrays! 原题链接 An array a is good if for all pairs of adjacent elements【相邻元素】, ai and ai+1 (1≤i<n) are of different parity【奇偶性】. 阅读全文