旋转二维矩形阵列的就地 [英] Rotate 2D rectangular array in-place
问题描述
我有一个非方形阵列是这样的:
I have an non-square array like this:
const int dim1 = 3, dim2 = 4;
int array[12] = { 1, 2, 3,
4, 5, 6,
7, 8, 9,
10,11,12};
和我需要将其转换为:
{3,6,9,12,
2,5,8,11,
1,4,7,10}
这就是旋转/洗牌它逆时针(或顺时针,算法应该是similiar)。
that is, rotate/shuffle it counter-clockwise (or clockwise, the algorithm should be similiar).
该算法应使用的最小空间。我必须在一个非常内存受限的环境下旋转图像,所以更少的空间就更好了。速度不是大问题。
The algorithm should use a minimal amount of space. I have to rotate an image in an extremely memory-constrained environment, so the less space the better. Speed is not as big an issue.
推荐答案
您可以转就地矩阵(见<一href=\"http://en.wikipedia.org/wiki/In-place_matrix_transposition\">http://en.wikipedia.org/wiki/In-place_matrix_transposition)再反向行是微不足道的。
You can transpose the matrix in-place (see http://en.wikipedia.org/wiki/In-place_matrix_transposition) and then reverse the rows which is trivial.
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