Count Elements With Strictly Smaller and Greater Elements

Problem Description

Given an integer array nums, return the number of elements that have both a strictly smaller and a strictly greater element appear in nums.

Key Insights

• An element in the array should have at least one element that is smaller and one that is greater than itself.
• The minimum and maximum elements in the array are critical because they cannot have both a strictly smaller and a strictly greater element.
• Counting the occurrences of elements can help determine how many elements meet the criteria.

Space and Time Complexity

Time Complexity: O(n)
Space Complexity: O(1)

Solution

To solve the problem, we can follow these steps:

1. Identify the minimum and maximum values in the array.
2. Count the number of elements that are neither the minimum nor the maximum.
3. Return that count, as these are the elements that have both a strictly smaller and a strictly greater element.

This approach uses constant space and requires a single pass through the array to determine the minimum and maximum values, followed by another pass to count the qualifying elements.

Code Solutions