Top K Frequent Elements

Yoges — Thu, 17 Sep 2026 16:08:13 +0000

Today i try to solve Top K Frequent Elements the problem is simple you need to return the k most frequent elements.

Problem:

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

The test cases are generated such that the answer is always unique.

You may return the output in any order.

Solution:

I choose HashMap to track the frequency of the element

Then we need to take the largest k elements
this is the tricky part

How can i get the largest value(count of the element) from the map and store the exact k largest values??

Then i endup with Min Heap. But the challenge is store the key, value pairs in Priority Queue.
For that i use map.entry to store in Priority Queue it compares the values in the map. It's sounds confusing but it too easy..

JAVA code:

class Solution {
    public int[] topKFrequent(int[] nums, int k) {
        HashMap<Integer, Integer> map = new HashMap<>();
        //we have to return most frequent elements.Elements count should be k
        //ex: k=2 you have to return 2 element. that element should be have most frequency

        //step 1: store the element with frequency as a key, value pair in map
        for(int num : nums){
            map.put(num, map.getOrDefault(num, 0)+1);
        }

        //Use MinHeap to get the most frequent value
        // the will be store k elements if the size of pq > k we need remove smallest element so just use poll method to remove it.

        PriorityQueue<Map.Entry<Integer, Integer>> pq =
                    new PriorityQueue<>(
                        Comparator.comparingInt(Map.Entry::getValue) // pq compare the value here we are storing the map entry so we need to mentain which value should be compared here
                        //Here we need compare the values inorder to get the highest frequency
                    );

         for(Map.Entry<Integer, Integer> entry : map.entrySet()){
            pq.offer(entry);
            if(pq.size() > k){
                pq.poll();
            }
         }
         int[] ans = new int[k];
         int i = 0;
        // Then finally store it in array return it
         while(!pq.isEmpty()){
             Map.Entry<Integer, Integer> entry = pq.poll();
             ans[i++] = entry.getKey();
         }
         return ans;
    }
}

How i learn to how to learn?!😵

Yoges — Wed, 16 Sep 2026 09:19:08 +0000

I learned about HTML, CSS, JS.

Mostly I start learning using tutorials. Yeah, it's hell. At the end of the video, I learned about nothing, just a few pieces of memorized knowledge. But this time I dig into a different way. I use the dev challenge devchallenges to read the article and then build it with no AI involved, just me and that article. Sometimes I get stuck between thoughts, and then I use the world's most powerful tool, GOOGLE. Yeah, you read it correctly. I use Google, Stack Overflow, etc. This thing taught me how to solve your problem using your brain, not an AI's brain.

TIPS FOR THE PAST ME

Read other people's code and understand it. (The more you read it, the less you ask AI.)
There are endless possibilities to learn in today's tech world; just utilize it.

https://www.w3schools.com/
https://developer.mozilla.org/en-US/ I mainly use these two for theory stuffs of HTML, CSS, JS. you can prefer whatever you want like GFG,..etc

(I am not good at English. Forgive me if anything is wrong.)

DEV Community: Yoges

Top K Frequent Elements

Problem:

Solution:

How i learn to how to learn?!😵