306920: CF1270I. Xor on Figures
Memory Limit:256 MB
Time Limit:5 S
Judge Style:Text Compare
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Description
Xor on Figures
题意翻译
有一个 $2^k\times 2^k$ 的矩阵 $A$,行列从 $0$ 开始标号,有两个长度为 $t$ 的序列 $x,y$。 你需要通过若干次操作使得整个矩阵 $A$ 全为 $0$。 一次操作需要三个参数 $(p,q,w)$,会给所有 $A[(x_i+p)\bmod 2^k][(y_i+q)\bmod 2^k]$ 异或上 $w$。 求最小的操作次数。 $k\le 9,t\le 99$ 且 $t$ 为奇数。题目描述
There is given an integer $ k $ and a grid $ 2^k \times 2^k $ with some numbers written in its cells, cell $ (i, j) $ initially contains number $ a_{ij} $ . Grid is considered to be a torus, that is, the cell to the right of $ (i, 2^k) $ is $ (i, 1) $ , the cell below the $ (2^k, i) $ is $ (1, i) $ There is also given a lattice figure $ F $ , consisting of $ t $ cells, where $ t $ is odd. $ F $ doesn't have to be connected. We can perform the following operation: place $ F $ at some position on the grid. (Only translations are allowed, rotations and reflections are prohibited). Now choose any nonnegative integer $ x $ . After that, for each cell $ (i, j) $ , covered by $ F $ , replace $ a_{ij} $ by $ a_{ij}\oplus x $ , where $ \oplus $ denotes the [bitwise XOR operation](https://en.wikipedia.org/wiki/Bitwise_operation#XOR). More formally, let $ F $ be given by cells $ (x_1, y_1), (x_2, y_2), \dots, (x_t, y_t) $ . Then you can do the following operation: choose any $ x, y $ with $ 1\le x, y \le 2^k $ , any nonnegative integer $ x $ , and for every $ i $ from $ 1 $ to $ n $ replace number in the cell $ (((x + x_i - 1)\bmod 2^k) + 1, ((y + y_i - 1)\bmod 2^k) + 1) $ with $ a_{((x + x_i - 1)\bmod 2^k) + 1, ((y + y_i - 1)\bmod 2^k) + 1}\oplus x $ . Our goal is to make all the numbers equal to $ 0 $ . Can we achieve it? If we can, find the smallest number of operations in which it is possible to do this.输入输出格式
输入格式
The first line contains a single integer $ k $ ( $ 1 \le k \le 9 $ ). The $ i $ -th of the next $ 2^k $ lines contains $ 2^k $ integers $ a_{i1}, a_{i2}, \dots, a_{i2^k} $ ( $ 0 \le a_{ij} < 2^{60} $ ) — initial values in the $ i $ -th row of the grid. The next line contains a single integer $ t $ ( $ 1\le t \le \min(99, 4^k) $ , $ t $ is odd) — number of cells of figure. $ i $ -th of next $ t $ lines contains two integers $ x_i $ and $ y_i $ ( $ 1 \le x_i, y_i \le 2^k $ ), describing the position of the $ i $ -th cell of the figure. It is guaranteed that all cells are different, but it is not guaranteed that the figure is connected.
输出格式
If it is impossible to make all numbers in the grid equal to $ 0 $ with these operations, output $ -1 $ . Otherwise, output a single integer — the minimal number of operations needed to do this. It can be shown that if it is possible to make all numbers equal $ 0 $ , it is possible to do so in less than $ 10^{18} $ operations.
输入输出样例
输入样例 #1
2
5 5 5 5
2 6 2 3
0 0 2 0
0 0 0 0
5
1 1
1 2
1 3
1 4
2 4
输出样例 #1
3