Given a list of non negative integers, arrange them such that they form the largest number.
For example, given [3, 30, 34, 5, 9], the largest formed number is 9534330.
Note: The result may be very large, so you need to return a string instead of an integer.
Credits:
Special thanks to @ts for adding this problem and creating all test cases.
http://www.bubuko.com/infodetail-579261.html
http://www.cnblogs.com/easonliu/p/4221810.html[LeetCode] Largest Number 最大组合数
原文：http://www.cnblogs.com/grandyang/p/4225047.html
