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.

思路：一个数列到第i位的最大子集和为：i位元素和减去第i位之前的最小和。遍历并比较各位的最大子集合，最大的值为答案。

Solution:

public class Solution {    public int maxSubArray(int[] A) {        if (A == null || A.length == 0) {            return 0;        }                int preSum = 0;        int sum = 0;        int max = Integer.MIN_VALUE;        for (int i = 0; i < A.length; i++) {            sum += A[i];            max = Math.max(max, sum - preSum);            preSum = Math.min(preSum, sum);        }                return max;    }}