Java实现MXN矩阵顺时针旋转

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Java实现MXN矩阵顺时针旋转

矩阵，可以看做是一个二维数组，如何实现一个MXN的矩阵旋转,如顺时针旋转90°，180°，270°。

3X4 矩阵 ：

int[][] matrix = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}};

顺时针90°,为4X3矩阵：{{9, 5, 1}, {10, 6, 2}, {11, 7, 3}, {12, 8, 4}}

顺时针180°,为3X4矩阵：{{12, 11, 10, 9}, {8, 7, 6, 5}, {4, 3, 2,1}}

顺时针270°,为4X3矩阵：{{4, 8, 12}, {3, 7, 11}, {2, 6, 10}, {1, 5, 9}}

代码如下：

package com.yx.test.util;public class MatrixUtil {public enum Rotation {/*** 不旋转*/ROTATION_0,/*** 右转90度*/ROTATION_90,/*** 右转180度*/ROTATION_180,/*** 右转270度*/ROTATION_270}/*** 点阵旋转** @param ori      原始点阵* @param rotation 旋转后点阵* @return 旋转后的点阵*/private static int[][] rotation(int[][] ori, Rotation rotation) {if (rotation == null || ori == null) {return null;}int row = ori.length;int col = ori[0].length;int[][] ret = null;switch (rotation) {case ROTATION_0:ret = ori;break;case ROTATION_90:ret = new int[col][row];for (int i = 0; i < row; i++) {for (int j = 0; j < col; j++) {ret[j][row - 1 - i] = ori[i][j];}}break;case ROTATION_180:ret = new int[row][col];for (int i = 0; i < row; i++) {for (int j = 0; j < col; j++) {ret[row - 1 - i][col - 1 - j] = ori[i][j];}}break;case ROTATION_270:ret = new int[col][row];for (int i = 0; i < row; i++) {for (int j = 0; j < col; j++) {ret[col - 1 - j][i] = ori[i][j];}}break;default:break;}return ret;}/*** 打印矩阵* @param matrix 待打印矩阵*/private static void printMatrix(int[][] matrix) {if (matrix != null) {int row = matrix.length;int col = matrix[0].length;for (int i = 0; i < row; i++) {for (int j = 0; j < col; j++) {System.out.print(matrix[i][j] + " ");}System.out.println();}System.out.println();}}public static void main(String[] args) {int[][] matrix = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}};printMatrix(matrix);int[][] matrix90 = rotation(matrix, Rotation.ROTATION_90);printMatrix(matrix90);int[][] rotationMatrix180 = rotation(matrix, Rotation.ROTATION_180);printMatrix(rotationMatrix180);int[][] rotationMatrix270 = rotation(matrix, Rotation.ROTATION_270);printMatrix(rotationMatrix270);}
}

转换的关系式可以通过坐标系转换的思想理解。