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Solution: Next Greater Element IV

Explore the stack data structure approach to solve the Next Greater Element IV problem. This lesson helps you understand how to efficiently find the second greater element for each number in an array using two stacks, ensuring a linear time solution. You'll develop skills to track elements in different states and optimize your coding solutions for interview success.

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:

  • ...