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.

思路一：

不定长的滑动窗口，如果前面的sum值小于零了，说明对于之后的sum值计算产生减少的效果，所以此时将sum置0，每次都更新max值。

public int maxSubArray(int[] A) {
        int sum = 0;
        int max = Integer.MIN_VALUE;
        for(int i=0; i<A.length; i++) {
            sum += A[i];
            max = Math.max(max, sum);
            sum = Math.max(sum, 0);
        }
        return max;
    }