LeetCode: Maximum Subarray 解題報告

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.

SOLUTION 1:

采用滑動窗口解決。sum 如果小於0，置為0，再加上當前值。

然后再與max相比，取大的。 1分鍾AC

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

https://github.com/yuzhangcmu/LeetCode_algorithm/blob/master/array/MaxSubArray_1220_2014.java