sky123博客

You are given a table a of size 2×n2×n2×n (i.e. two rows and n columns) consisting of integers from 111 to nnn. In one move, you can choose some column jjj (1≤j≤n)(1≤j≤n)(1≤j≤n) and swap values a1,ja_{1,j}a1,j​ and a2,ja_{2,j}a2,j​ in it. Each column can b

You inherited a haunted house. Its floor plan is an nnn-by-nnn square grid with lll lamps in fixedlocations and no interior walls. Each lamp can either illuminate its row or its column, but not bothsimultaneously. The illumination of each lamp extends by r