Top K Frequent Elements

Given an array and an integer k, return the k most frequent elements.

Example

Input: 1 1 1 2 2 3, k = 2 Output: 1 2

Approach

Count each value's frequency with a hash map, then find the k keys with the highest counts — a heap keyed on frequency does this in O(n log k) without a full sort of every distinct value.

Input format

Line 1: the array, space-separated Line 2: k

Print the k most frequent values, space-separated, sorted ascending for a deterministic check.