def aa(matrix):
rows=len(matrix)
cols=len(matrix[0])
start=0
ret=[]
while start*2 <rows and start*2<cols:
bb(matrix,rows,cols,start,ret)
start +=1
return ret
def bb(matrix,rows,cols,start,ret):
row=rows-start-1
col=cols-start-1
for c in range(start,col+1):
ret.append(matrix[start][c])
if start <row:
for r in range(start+1,row+1):
ret.append(matrix[r][col])
if start <row and start<col:
for c in range(start,col)[::-1]:
ret.append(matrix[row][c])
if start <row and start<col:
for r in range(start+1,row)[::-1]:
ret.append(matrix[r][start])
a=[[1,2,3],
[4,5,6],
[7,8,9]]
print(aa(a))
