TLE, 比较efficient的做法是stack，但是不太会用stack解这个，看别人怎么做吧~
Merge branch 'master' of https://github.com/JenniferWang/algorithmPractice

Conflicts:
	LongestValidParentheses.py
Merge branch 'master' of https://github.com/JenniferWang/algorithmPractice