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;     }}*/