LintCode-41.Maximum Subarray
[http://www.lintcode.com/en/problem/maximum-subarray/]
> Given an array of integers, find a contiguous subarray which has the largest
sum.
> Notice: The subarray should contain at least one number.
> Given the array [−2,2,−3,4,−1,2,1,−5,3], the contiguous subarray [4,−1,