The Maximum Ascending Subarray Sum problem provides an array of positive integers. You need to find the maximum possible sum of a contiguous subarray where the elements are strictly ascending (meaning each element is strictly greater than the preceding one). For example, in [10, 20, 30, 5, 10, 50], the ascending subarrays are [10, 20, 30], [5, 10, 50]. You must return the highest sum among them.
This is a standard Easy-level screening question. Interviewers use it to assess basic coding fluency, loop mechanics, and state tracking. It ensures a candidate can differentiate between a "subsequence" (can skip elements) and a "subarray" (must be contiguous) and can properly reset running totals when a condition is broken.
This problem relies on a Single Pass / Sliding Window pattern. You maintain a current_sum and a max_sum. You iterate through the array starting from index 0. If the current element is strictly greater than the previous element, you add it to current_sum. If it is less than or equal to the previous element, the ascending chain is broken. You update max_sum, and reset current_sum to the value of the current element (because it starts a new chain).
Array: [10, 20, 30, 5, 10, 50]
Initialize: curr_sum = 10 (first element), max_sum = 10.
20): . Ascending! curr_sum = 10 + 20 = 30. max_sum = 30.30): . Ascending! curr_sum = 30 + 30 = 60. max_sum = 60.5): is NOT . Chain breaks! Update max_sum = max(60, 60) = 60. Reset curr_sum = 5.10): . Ascending! curr_sum = 5 + 10 = 15.50): . Ascending! curr_sum = 15 + 50 = 65. max_sum = max(60, 65) = 65.
The maximum ascending subarray sum is 65.A common error for beginners is resetting the curr_sum to 0 when the chain breaks. If you hit a number that breaks the chain (like the 5 in the example), that 5 is actually the first element of the next potential chain! You must reset the curr_sum to arr[i], not 0. Another mistake is forgetting to do a final max_sum = Math.max(max_sum, curr_sum) check after the loop ends to account for arrays that are entirely ascending.
For the Maximum Ascending Subarray Sum interview question, you can avoid the "post-loop check" bug entirely by updating your max_sum inside every iteration of the loop, rather than only when the chain breaks. Doing max_sum = Math.max(max_sum, curr_sum); universally at the bottom of your for loop keeps the code exceptionally clean and bug-proof.