[Java] java编程题之顺时针打印矩阵

import java.util.arraylist;
 
/**
 * 
 * 剑指offer编程题（java实现)——第19题：顺时针打印矩阵
 * 
 * 题目描述
输入一个矩阵，按照从外向里以顺时针的顺序依次打印出每一个数字，例如，
如果输入如下4 x 4矩阵： 
1 2 3 4 
5 6 7 8 
9 10 11 12 
13 14 15 16 
则依次打印出数字1,2,3,4,8,12,16,15,14,13,9,5,6,7,11,10.
 *
 */
public class test19 {
 
 public static void main(string[] args) {
 int[][] array1 = { { 1, 2, 3, 4 }, { 5, 6, 7, 8 }, { 9, 10, 11, 12 }, { 13, 14, 15, 16 } };
 int[][] array2 = { { 1 } };
 int[][] array3 = { { 1 }, { 2 }, { 3 }, { 4 }, { 5 } };
 int[][] array4 = { { 1, 2, 3, 4, 5 } };
 int[][] array5 = { { 1, 2, 3, 4, 5 }, { 6, 7, 8, 9, 10 }, { 11, 12, 13, 14, 15 } };
 printmatrix(array1);
 system.out.println();
 printmatrix(array2);
 system.out.println();
 printmatrix(array3);
 system.out.println();
 printmatrix(array4);
 system.out.println();
 printmatrix(array5);
 
 }
 
 public static arraylist<integer> printmatrix(int[][] matrix) {
 arraylist<integer> arraylist = new arraylist<>();
 int x = 0;
 int row = matrix.length;
 int line = matrix[matrix.length - 1].length;
 while (x < row && x < line) {
  arraylist.addall(printline(matrix, x, x, row, line));
  x++;
  row--;
  line--;
 }
 
 system.out.print(arraylist.tostring());
 return arraylist;
 
 }
 
 private static arraylist<integer> printline(int[][] matrix, int r1, int l1, int r2, int l2) {
 arraylist<integer> arraylist = new arraylist<>();
 for (int i = l1; i <= l2 - 1; i++) {// 保证奇数层中间可输出
  arraylist.add(matrix[r1][i]);
 }
 
 for (int k = r1 + 1; k <= r2 - 1; k++) {
  arraylist.add(matrix[k][l2 - 1]);
 }
 if ((r2 - r1) != 1) {//防止重复打印
  for (int j = l2 - 2; j >= l1; j--) {
  arraylist.add(matrix[r2 - 1][j]);
  }
 }
 
 if ((l2 - l1) != 1) {//防止重复打印
  for (int u = r2 - 2; u > r1; u--) {
  arraylist.add(matrix[u][l1]);
  }
 }
 
 return arraylist;
 }
}
//其他方法
/**
import java.util.arraylist;
public class solution {
  public arraylist<integer> printmatrix(int [][] array) {
  arraylist<integer> result = new arraylist<integer> ();
  if(array.length==0) return result;
  int n = array.length,m = array[0].length;
  if(m==0) return result;
  int layers = (math.min(n,m)-1)/2+1;//这个是层数
  for(int i=0;i<layers;i++){
    for(int k = i;k<m-i;k++) result.add(array[i][k]);//左至右
    for(int j=i+1;j<n-i;j++) result.add(array[j][m-i-1]);//右上至右下
    for(int k=m-i-2;(k>=i)&&(n-i-1!=i);k--) result.add(array[n-i-1][k]);//右至左
    for(int j=n-i-2;(j>i)&&(m-i-1!=i);j--) result.add(array[j][i]);//左下至左上
  }
  return result;   
  }
}
 
*/