Solution: Next Greater Element I

Explore how to solve the Next Greater Element problem by implementing an optimized algorithm using a hash map and a monotonic stack. Understand how to improve from a naive quadratic approach to a linear time solution by efficiently tracking elements and their next greater values. This lesson guides you through the problem statement, challenges, and step-by-step implementation while analyzing time and space complexities.

We'll cover the following...

Statement
Solution
- Naive approach
- Optimized approach using hash map

Statement

Given the two distinct integer arrays, nums1 and nums2, where nums1 is a subset of nums2, find all the next greater elements for nums1 values in the corresponding places of nums2.

In general, the next greater element of an element, $x$ , in an array is the first greater element present on the right side of $x$ in the same array. However, in the context of this problem, for each element $x$ in nums1, find the next greater element present on the right side of $x$ in nums2 and store it in the ans array. If there is no such element, store ...