POJ 755——Flip Game 有一块4*4的棋盘，每个格子上有一个黑色或白色的棋子，翻转一个棋子会使这个棋子及周围的4个棋子变为相反的颜色，给定棋盘的初始状态，求将棋盘中的格子都变为黑色或白色的最少翻转次数。-POJ 755- Flip Game has a 4* 4 chessboard, each grid on a black or white piece, flip a pawn makes this piece and around 4 pawn becomes the opp