1800. Maximum Ascending Subarray Sum

Time: O(n)

Space: O(1)

Intuition

Find the subarray of 1s with maximum length (since max sum of consecutive ascending array starting from 1 = 1+2+...+L = L*(L+1)/2 but actually just sum consecutive increasing prefix).

Algorithm

1Sliding window: longest consecutive subarray where each element = previous + 1.
2Max sum = max(sum of such a window).

Common Pitfalls

•The maximum ascending subarray sum (each element strictly greater than previous).

1800.cs

// Approach: Linear scan maintaining running sum of current ascending subarray; reset on non-increase.
// Time: O(n) Space: O(1)

public class Solution
{
    public int MaxAscendingSum(int[] nums)
    {
        int maxSum = 0;
        int sum = nums[0];

        for (int i = 1; i < nums.Length; i++)
        {
            if (nums[i] > nums[i - 1])
                sum += nums[i];
            else
            {
                maxSum = Math.Max(maxSum, sum);
                sum = nums[i];
            }
        }

        return Math.Max(maxSum, sum);
    }
}

Was this solution helpful?