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Farmer John has invented a game, Chessboard Puzzle, which perplexes lots of puzzle fanatics. The game is quite simple. Given a chessboard in such a way that every grid is presented by a specified integer, you are obliged to color every grid in white or black. For each pair of grids subjected to following restraints:
add the product of the two specified integers to the score. And your goal is to maximum the total score. Could you write a program to tell John the maximum score?
The input describes one puzzle which begins with two integer n, m(1 ≤ n, m ≤16). Then n lines follow. Each contains m integers. The j-th number on i-th row corresponds to the grid(i,j). The absolute value of each number is less than 1000.
Print the maximum score in a line.
5 5 -136 -712 -286 -622 564 6 -899 623 -152 -519 904 982 593 799 93 -815 122 -307 572 -359 921 757 -888 351 935
5852863
| 时间上限 | 内存上限 |
| 2000 | 131072 |