给定一个2n*2n的残缺棋盘，问如何放置三格板，使得除残缺格外，棋盘中其他格子都被三格板覆盖，并且放置的三格板互不重叠。-Given the deterioration of a 2n* 2n board, and asked how to place three cell plate, making the extra addition to incomplete, the board were three other lattice grid plate coverage, and placed the three non-overlapping grid plate.