53. Maximum Subarray (JAVA)

iven an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.

Example:

Input: [-2,1,-3,4,-1,2,1,-5,4],
Output: 6
Explanation: [4,-1,2,1] has the largest sum = 6.

Follow up:

If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.

class Solution {
    public int maxSubArray(int[] nums) {
        int maxSum = Integer.MIN_VALUE; //注意有负数的时候，不能初始化为0
        int currentSum = Integer.MIN_VALUE;
        for(int i = 0; i < nums.length; i++){
            if(currentSum < 0) currentSum = nums[i];
            else currentSum += nums[i];
            
            if(currentSum > maxSum) maxSum = currentSum; 
        }
        return maxSum;
    }
}