JZ19 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.

import java.util.ArrayList;
public class Solution {
            public ArrayList<Integer> printMatrix(int[][] matrix) {

        ArrayList arrayList = new ArrayList();
        int startRow = 0;
        int endRow = matrix.length-1;
        int startColumn = 0;
        int endColumn = matrix[0].length-1;


        while (startRow <= endRow && startColumn <= endColumn){
            for (int i = startColumn; i <= endColumn; i++) {
                arrayList.add(matrix[startRow][i]);
            }
            for (int i = startRow+1; i <= endRow; i++) {
                arrayList.add(matrix[i][endColumn]);
            }
            if (startRow == endRow) {
                return arrayList;
            }
            for (int i = endColumn-1; i >= startColumn; i--) {
                arrayList.add(matrix[endRow][i]);
            }
            if (startColumn == endColumn) {
                return arrayList;
            }
            for (int i = endRow-1; i >= startRow+1; i--) {
                arrayList.add(matrix[i][startColumn]);
            }
            startRow++;
            startColumn++;
            endRow--;
            endColumn--;
        }
        return arrayList;
    }

}