CODE 85. Rotate Image

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版权声明：本文为博主原创文章，转载请注明出处：http://blog.jerkybible.com/2013/10/19/2013-10-19-CODE 85 Rotate Image/

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You are given an n x n 2D matrix representing an image.
Rotate the image by 90 degrees (clockwise).
Follow up:
Could you do this in-place?

public void rotate(int[][] matrix) {
	// Start typing your Java solution below
	// DO NOT write main() function
	if (null == matrix || matrix.length <= 0) {
		return;
	}
	int roll = (matrix.length - 1) / 2;
	for (int i = 0; i <= roll; i++) {
		for (int k = i; k < matrix.length - i - 1; k++) {
			int tmp = matrix[i][k];
			matrix[i][k] = matrix[matrix.length - k  - 1][i];
			matrix[matrix.length - k  - 1][i] = matrix[matrix.length
					- i - 1][matrix.length - k  - 1];
			matrix[matrix.length - i - 1][matrix.length - k - 1] = matrix[k][matrix.length
					- i - 1];
			matrix[k][matrix.length - i - 1] = tmp;
		}
	}
}