Leetcode-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.

Analysis:

We define the state d[i] as the the largest sum we can get for subarrays the end at i. We then have the formula:

if d[i-1]<0, then we will choose to just select A[i] at i, d[i]=A[i]; otherwise d[i]=A[i]+d[i-1];

Solution:

public class Solution {
    public int maxSubArray(int[] A) {
        int len = A.length;
        if (len==0) return 0;
        int[] d = new int[len];
        d[0] = A[0];
        int max = d[0];
        for (int i=1;i<len;i++){
            if (d[i-1]<0)
                d[i]=A[i];
            else 
                d[i]=A[i]+d[i-1];
            if (d[i]>max) max = d[i];
        }

        return max;
    }
}