(AtCoder Beginner Contest 375)C - Spiral Rotation给定二维数组 a [ n ] [ n ] , n m o d 2 = 0 a[n][n],n \mod 2=0 a[n][n],nmod2=0 执行 i = 1 , 2 , . . . i=1,2,... i=1,2,... n / 2 n/2 n/2 操作 每次操作对于 ∀ x , y ∈ [ i , n + 1 − i ] \forall x,y\in[i,n+1-i] ∀x,y∈[i,n+1−i] 将 a [ y ] [ n + 1 − x ] a[y][n+1-x] a[y][n+1−x]替