• output error messages to stderr instead of stdout.

修复 leetcode / leetocde add 命令时，渲染 reamd.md 文件中表格的title错误

1. 250 leetcodes

1.fix regular matching of READMD.md failed, unable to parse the 难度 field

1. add difficulty of leetcode in readme.md
2. Optimize the code

1.rebuild leetcode script
2.new format in readme.md