Flip Game(枚举)Poj

Flip Game

Time Limit: 1000MS		Memory Limit: 65536K
Total Submissions: 31329		Accepted: 13622

DescriptionFlip game is played on a rectangular 4x4 field with two-sided pieces placed on each of its 16 squares. One side of each piece is white and the other one is black and each piece is lying either it's black or white side up. Eachround you flip 3 to 5 pieces, thus changing the color of their upper side from black to white and vice versa. The pieces to be flipped are chosen every round according to the following rules:Choose any one of the 16 pieces.Flip the chosen piece and also all adjacent pieces to the left, to the right, to the top, and to the bottom of the chosen piece (if there are any).Consider the following position as an example:bwbwwwwwbbwbbwwbHere "b" denotes pieces lying their black side up and "w" denotes pieces lying their white side up. If we choose to flip the 1st piece from the 3rd row (this choice is shown at the picture), then the field will become:bwbwbwwwwwwbwwwbThe goal of the game is to flip either all pieces white side up or all pieces black side up. You are to write a program that will search for the minimum number of rounds needed to achieve this goal.InputThe input consists of 4 lines with 4 characters "w" or "b" each that denote game field position.OutputWrite to the output file a single integer number - the minimum number of rounds needed to achieve the goal of the game from the given position. If the goal is initially achieved, then write 0. If it's impossible to achieve thegoal, then write the word "Impossible" (without quotes).Sample Input

4

题意：有16个硬币  每一个硬币哟两种颜色（黑色b白色w），翻转当中不论什么一个硬币。其上下左右的硬币也要翻转，要求翻转最少的次数使全部的硬币达到同一种颜色，否则输出Impossible

艾玛 做了好长时间 加上大牛们的见解（让1为黑色 0为白色）  最终做出来了

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