【美团面试】java实现二维数组逆时针回形遍历

public static void main(String[] args){
int a[][] = {
{1,2,3,4},
{5,6,7,8},
{9,10,11,12},
{13,14,15,16},
{17,18,19,20}
};
int time=0;  //5行4列，输出顺序为1,2,3,4,8,12,16,20,19,18,17,13,9,5,6,7,11,15,。。
int M=a.length;
int N=a[0].length;
int j=0;

for(int n=0;;n++){
for(j=n;j<N-n;j++){
time++;
System.out.println(a
[j]);
}
if(time==M*N)
break;

for(j=n+1;j<M-n;j++){
time++;
System.out.println(a[j][N-n-1]);
}
if(time==M*N)
break;

for(j=N-n-2;j>=n;j--){
time++;
System.out.println(a[M-n-1][j]);
}
if(time==M*N)
break;

for(j=M-n-2;j>=n+1;j--){
time++;
System.out.println(a[j]
);
}
if(time==M*N)
break;
}
}