CCI 1.6 旋转矩阵

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给定一幅由N*N矩阵表示的图像，其中每个像素的大小为4字节，编写一个方法，将图像旋转90度。不占用额外内存空间能否做到？

package test;public class RotateMatrix {public static void rotateMatrix(int[][] matrix){if(matrix==null || matrix.length==0 || matrix[0]==null || matrix[0].length==0)return;if(matrix.length != matrix[0].length)return;int n = matrix.length;for(int layer=0; layer < n/2; layer++){int first = layer;int last = n-layer-1;for(int i=first; i<last; i++){int offset = i-first;int temp = matrix[i][first];matrix[i][first] = matrix[last][i];matrix[last][i] = matrix[last-offset][last];matrix[last-offset][last] = matrix[first][last-offset];matrix[first][last-offset] = temp;}}}public static void main(String[] args) {// TODO Auto-generated method stubint[][] case1 = null;int[][] case2 = { {1,2,3}, {4,5,6}, {7,8,9} };int[][] testCase = case2;rotateMatrix(testCase);for(int i=0; i<testCase.length; i++){for(int j=0; j<testCase[0].length; j++){System.out.print(testCase[i][j]);System.out.print(" ");}System.out.println();}}}

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