Leetcode 252 Meeting Rooms

Given an array of meeting time intervals consisting of start and end times  [[s1,e1],[s2,e2],...] (s i < e i), determine if a person could attend all meetings.

For example,
Given  [[0, 30],[5, 10],[15, 20]],
return  false.

Understand the problem:

The problem looks very similar to the merge interval and insert intervals. So the idea is still the same: first sort the intervals according to the start times, then check if there is any overlap. 

所以正确的解法是将intervals中所有的interval都按start time进行排序，然后判断是否有overlap，如果有overlap就返回false，否则返回true。

The idea is from here

http://buttercola.blogspot.com/2015/08/leetcode-meeting-rooms.html