Least Number of Unique Integers after K Removals - Solution & Explanation

This approach involves two main steps. First, count the frequency of each integer in the array. Second, use a min-heap (or priority queue) to remove the integers with the smallest frequency first. This approach ensures that we are removing the least frequent integers to reach the least number of unique integers efficiently.

This C program implements the approach by utilizing an array to keep the frequency of each integer. It then collects these frequencies into another array which is sorted to allow removal of the lowest frequencies first. A loop continues removing these and reducing the count of unique integers. A direct index is maintained to access frequencies in order.

This approach takes a greedy strategy to count frequencies of integers and sorts them. By progressively removing elements with smallest frequencies, it directly calculates the least number of unique integers remaining after exactly k removals.

This implementation in C uses a frequency array to count each integer's occurrences. After sorting this array, elements are removed from the smallest frequency upwards until k removals are exhausted.