顺时针打印矩阵

问题描述

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.

 

import java.util.ArrayList;
import java.util.Collections;

public class Solution {
    
    public  ArrayList<Integer> printMatrix(int[][] numbers){
        if (numbers == null || numbers.length == 0){
            return new ArrayList<Integer>();
        }

        int columns = numbers[0].length;
        int rows = numbers.length;
        int start = 0;
        ArrayList<Integer> result = new ArrayList<Integer>();
        while (start * 2 < columns && start * 2 < rows) {
            solution(numbers, rows, columns, start, result);
            start++;
        }
        
        return result;
    }

    public void solution(int[][] numbers, int rows, int columns,int start, ArrayList<Integer> result) {
        
        int endX = columns - 1 - start;
        int endY = rows - 1 - start;
        for(int i = start; i <= endX; i++){
            result.add(numbers[start][i]);
        }
        
        if(endY > start){
            for(int i = start+1; i<= endY; i++){
                result.add(numbers[i][endX]);
            }
        }
        
        if(endY > start && endX > start){
            for(int i  = endX-1 ; i>= start; i--){
                result.add(numbers[endY][i]);
            }
        }
        
        if(endY - 1 > start && endX > start){
            for(int i = endY-1; i >= start+1 ; i--){
                result.add(numbers[i][start]);
            }
        }
    }
}