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Solution: Next Greater Element IV

Explore how to implement a stack-based solution to find the second greater element for each item in an integer array. Understand the use of two stacks to track elements waiting for the first and second greater values, optimizing your approach to solve this problem in linear time and space complexity. This lesson enhances your skills in solving advanced interview coding challenges efficiently.

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:

  • ...