描述：
Find the contiguous subarray within an array (containing at least one number) which has the largest sum.
For example, given the array [−2,1,−3,4,−1,2,1,−5,4],
the contiguous subarray [4,−1,2,1] has the largest sum = 6.
More practice:
If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle
代码：O（n）
class Solution {
public:
int maxSubArray(int A[], int n) {
// Note: The Solution object is instantiated only once and is reused by each test case.
int maxendinghere = 0,maxsofar = 0;
for(int i = 0; i<n; i++)
{
maxendinghere = max(maxendinghere + A[i],0);
maxsofar = max(maxsofar,maxendinghere);
}
if(maxsofar == 0) //数组元素全部非正数
{
int tmp = A[0];
for(int i = 1; i<n; i++)
{
tmp = max(tmp,A[i]);
}
return tmp;
}
return maxsofar;
}
};