print ('Hello world !!!')

square = 10
i = 1
flag = False
column = 0
row = 0
length = square * 2 - 1

while row < length:
while column < square:
if column < square - i:
print (' ', end = '')
elif column < square:
print ('*', end = '')
column += 1
print()

row += 1
column = 0
if flag == False:
i += 1
else:
i -= 1
if i > square:
i = square - 1
flag = True
print()

print('test')
print('DONE')


結果：