CodingHardcod-g528

Subject Monotonic stackLevel Senior–Staff~30 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given an array of positive integers, return the sum of the minimum element over every contiguous subarray, modulo 1_000_000_007. There are n*(n+1)/2 subarrays. The array has at least one element.

Implement

sum_subarray_mins(arr: list[int]) → int

Examples

in[[3,1,2,4]]out17

What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Learn the concepts

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.