[kuangbin带你飞]专题一 简单搜索 D - Fliptile poj 3279

D - Fliptile

Time Limit:2000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u

Submit Status Practice POJ 3279

Appoint description: System Crawler  (2015-11-08)

Description

Farmer John knows that an intellectually satisfied cow is a happy cow who will give more milk. 

He has arranged a brainy activity for cows in which they manipulate an M × N grid (1 ≤ M ≤ 15;

 1 ≤ N ≤ 15) of square tiles, each of which is colored black on one side and white on the other side.

As one would guess, when a single white tile is flipped, it changes to black; when a single black 

tile is flipped, it changes to white. The cows are rewarded when they flip the tiles so that each tile

 has the white side face up. However, the cows have rather large hooves and when they try to flip 

a certain tile, they also flip all the adjacent tiles (tiles that share a full edge with the flipped tile). 

Since the flips are tiring, the cows want to minimize the number of flips they have to make.

Help the cows determine the minimum number of flips required, and the locations to flip to achieve

 that minimum. If there are multiple ways to achieve the task with the minimum amount of flips,

 return the one with the least lexicographical ordering in the output when considered as a string. 

If the task is impossible, print one line with the word "IMPOSSIBLE".

Input

Line 1: Two space-separated integers: M and N
Lines 2.. M+1: Line i+1 describes the colors (left to right) of row i of the grid with N 

space-separated integers which are 1 for black and 0 for white

Output

Lines 1.. M: Each line contains N space-separated integers, each specifying how many 

times to flip that particular location.

Sample Input

4 41 0 0 10 1 1 00 1 1 01 0 0 1

Sample Output

0 0 0 01 0 0 11 0 0 10 0 0 0

题意：黑白的板，每次选择一个十字形翻转（十字板内黑白互换，若是边界则不管），

求最小将原图变为全白的策略。

题解：枚举第一行翻转情况，2^c，然后验证，由于第一行确定了，

后面就可以跟着确定了。