53. Maximum Subarray

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.

思路：这个题还挺经典，在Wikipedia上有对它的详细解释，并且给出了能AC的代码。从头至尾扫描数组，设当前扫描的元素为nums[i]，以max_ending_here记录结尾在元素i的连续数组的和，以max_so_far记录全程最大值，那么此时max_ending_here要么是原值加上当前值，要么是仅有当前值。