正如其他人所提到的，可能您的条件 line == '\n' 永远不会成立.正确的解决方案是使用如下循环:

As others have mentioned, probably your condition line == '\n' never holds true. The proper solution would be to use a loop like:

for line in sys.stdin:
  stripped = line.strip()
  if not stripped: break
  lines.append(stripped)