static String printElementsInSpiralOrder(int[][] matrix) { //time complexity: O(n)

String result = null;

List ans = new ArrayList<>();

if(matrix.length != 0){

int r1 = 0, r2 = matrix.length-1;

int c1 = 0, c2 = matrix[0].length-1;

while(r1<=r2 && c1<=c2){

for(int c=c1;c<=c2;c++)

ans.add(matrix[r1][c]);

for(int r = r1+1;r<=r2;r++)

ans.add(matrix[r][c2]);

if(r1<r2 && c1<c2){

for(int c = c2-1;c> c1;c--)

ans.add(matrix[r2][c]);

for(int r=r2;r> r1;r--)

ans.add(matrix[r][c1]);

}

r1++;

r2--;

c1++;

c2--;

}

}

result = ans.toString().replace(",", "");

return result;

}