源码
while (maxcount-- > 0) {
while (i < str_len && STRINGLIB_ISSPACE(str[i]))
i++;
if (i == str_len) break;
j = i; i++;
while (i < str_len && !STRINGLIB_ISSPACE(str[i]))
i++;
是O(n)
感谢:https://stackoverflow.com/questions/55113713/time-space-complexity-of-in-built-python-functions