常见面试算法之旋转打印矩阵

/**
* 面试常用题（一）
* 顺时针旋转矩阵
* @author Administrator
*
*/
public class Chapter01_rotateArray {
public static void rotate(int[][] matrix) {
int tR = 0;
int tC = 0;
int dR = matrix.length - 1;
int dC = matrix[0].length - 1;
while (tR < dR) {
rotateEdge(matrix, tR++, tC++, dR--, dC--);
}
}
public static void rotateEdge(int[][] m, int tR, int tC, int dR, int dC) {
int times = dC - tC; // times就是总共需要替换的次数
int tmp = 0;
for (int i = 0; i != times; i++) { // 一次循环就是一组占据调整
tmp = m[tC + i];
m[tC + i] = m[dR - i][tC];
m[dR - i][tC] = m[dR][dC - i];
m[dR][dC - i] = m[tR + i][dC];
m[tR + i][dC] = tmp;
}
}
public static void printMatrix(int[][] matrix) {
for (int i = 0; i != matrix.length; i++) {
for (int j = 0; j != matrix[0].length; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println();
}
}
public static void main(String[] args) {
int[][] matrix = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 },
{ 13, 14, 15, 16 } };
printMatrix(matrix);
rotate(matrix);
System.out.println("=========");
printMatrix(matrix);
rotate(matrix);
System.out.println("=========");
printMatrix(matrix);
rotate(matrix);
System.out.println("=========");
printMatrix(matrix);
}
}