Maximum Subarray

Given an integer array nums, find the subarray with the largest sum, and return its sum.

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

Example 2:
Input: nums = [1]
Output: 1
Explanation: The subarray [1] has the largest sum 1.

Example 3:
Input: nums = [5,4,-1,7,8]
Output: 23
Explanation: The subarray [5,4,-1,7,8] has the largest sum 23.

Constraints:

• 1 <= nums.length <= 105
• -104 <= nums[i] <= 104

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.

Approach

• Kadane's algorithm -> if sum negative then set it to zero
• For max sum initial to be set as first element
• Time: O(n) Space: O(1)

class Solution {
    public int maxSubArray(int[] nums) {
        int s = 0, m = nums[0];
        for (int n : nums) {
            if (s < 0)
                s = 0;
            s += n;
            m = Math.max(m, s);
        }
        return m;
    }
}