题解 | #顺时针打印数字矩阵#

import java.io.*;
import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        while(sc.hasNextInt()){
            int m = sc.nextInt();
            int n = sc.nextInt();
            if(m == -1 && n == -1){
                break;
            }
            int[][] dp = new int[m][n];

            for(int i = 0; i < m; ++i){
                for(int j = 0; j < n; ++j){
                    dp[i][j] = sc.nextInt();
                }
            }

            fun(dp);
        }
    }

    public static void fun(int[][] dp){
        StringBuilder sb = new StringBuilder();

        int m = dp.length;
        int n = dp[0].length;
        int r1 = 0, r2 = m - 1, c1 = 0, c2 = n - 1;
        while(r1 <= r2 && c1 <= c2){
            for(int i = c1; i <= c2; ++i){
                sb.append(dp[r1][i]+",");
            }

            for(int i = r1 + 1; i <= r2; ++i){
                sb.append(dp[i][c2]+",");
            }

            if(r1 != r2){
                for(int i = c2 - 1; i >= c1; --i){
                    sb.append(dp[r2][i]+",");
                }
            }

            if(c1 != c2){
                for(int i = r2 - 1; i >= r1 + 1; --i){
                    sb.append(dp[i][c1]+",");
                }
            }
            r1++;
            r2--;
            c1++;
            c2--;
        }

        System.out.println(sb.deleteCharAt(sb.length() - 1).toString());
    }
}