Search⌘ K
AI Features

Solution: Next Greater Element IV

Explore how to solve the Next Greater Element IV problem using stacks to track elements waiting for their first and second greater values. Learn to implement this efficient linear-time solution, understand its use of two stacks, and manage results with constant time operations per element for array processing.

Statement

You are given a 0-indexed array of non-negative integers nums. For each element nums[i], determine its second greater element and return an array res where res[i] contains the second greater element of nums[i].

The second greater element of nums[i] is defined as the value nums[j] such that:

  • j > i

  • nums[j] > nums[i]

  • There exists exactly one index k where i < k < j and nums[k] > nums[i]

If no such index j exists, then the second greater element for nums[i] is -1.

Constraints:

  • ...