53. Maximum Subarray

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

Example 1:

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

Example 2:

Input: nums = [1]
Output: 1

Example 3:

Input: nums = [0]
Output: 0

Example 4:

Input: nums = [-1]
Output: -1

Example 5:

Input: nums = [-100000]
Output: -100000

Constraints:

• 1 <= nums.length <= 3 * 104

• -105 <= nums[i] <= 105

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.

public class Solution {
    public int MaxSubArray(int[] nums) {
      if(nums == null){
        return 0;
      }
      if(nums.Length == 1){
        return nums[0];
      }
      
      var cur = nums[0];
      var sum = nums[0];
      
      for(int i = 1; i < nums.Length; i++){
        cur = cur > 0 ? cur + nums[i] : nums[i];
        if(cur >= sum){
          sum = cur;
        }
      }
      return sum;
    }
}