19-顺时针打印矩阵

1. 题目描述

2. 题解

---------------------------------------------【2021-08-08】更新----------------------------------------------------------

import java.util.ArrayList;
public class Solution {
    public ArrayList<Integer> printMatrix(int [][] matrix) {
        ArrayList<Integer> res=new ArrayList<>();
        ArrayList<Integer> tmp=new ArrayList<>();
        if(matrix.length==0)
            return tmp;
        int top=0;//横坐标
        int left=0;//纵
        int bottom=matrix.length-1;//横
        int right=matrix[0].length-1;//纵
        while(true)
        {
            //left -> right
            for(int j=left;j<=right;j++)
            {
                res.add(matrix[top][j]);
            }
            top++;
            if(top>bottom)
                break;//break跳出一层循环

            //top -> bottom
            for(int i=top;i<=bottom;i++)
            {
                res.add(matrix[i][right]);
            }
            right--;
            if(right<left)
                break;

            //right -> left
            for(int j=right;j>=left;j--)
            {
                res.add(matrix[bottom][j]);
            }
            bottom--;
            if(bottom<top)
                break;

            //bottom -> top
            for(int i=bottom;i>=top;i--)
            {
                res.add(matrix[i][left]);
            }
            left++;
            if(left>right)
                break;
        }
        return res;
    }
}