Top 'K' Frequent Numbers (medium)

Problem Statement

Given an unsorted array of numbers, find the top ‘K’ frequently occurring numbers in it.

Example 1:

Input: [1, 3, 5, 12, 11, 12, 11], K = 2
Output: [12, 11]
Explanation: Both '11' and '12' apeared twice.

Example 2:

Input: [5, 12, 11, 3, 11], K = 2
Output: [11, 5] or [11, 12] or [11, 3]
Explanation: Only '11' appeared twice, all other numbers appeared once.

Try it yourself

Try solving this question here:

import java.util.*;
class TopKFrequentNumbers {
  public static List<Integer> findTopKFrequentNumbers(int[] nums, int k) {
    List<Integer> topNumbers = new ArrayList<>(k);
    // TODO: Write your code here
    return topNumbers;
  }
  public static void main(String[] args) {
    List<Integer> result = TopKFrequentNumbers.findTopKFrequentNumbers(new int[] { 1, 3, 5, 12, 11, 12, 11 }, 2);
    System.out.println("Here are the K frequent numbers: " + result);
    result = TopKFrequentNumbers.findTopKFrequentNumbers(new int[] { 5, 12, 11, 3, 11 }, 2);
    System.out.println("Here are the K frequent numbers: " + result);
  }
}

Introduction

Pattern: Sliding Window

Pattern: Two Pointers

Pattern: Fast and Slow Patterns

Pattern: Merge Intervals

Pattern: Cyclic Sort

Pattern: In-place Reversal of a LinkedList

Pattern: Tree Breadth First Search

Pattern: Tree Depth First Search

Pattern: Two Heaps

Pattern: Subsets

Pattern: Modified Binary Search

Pattern: Bitwise XOR

Pattern: Top 'K' Elements

Pattern: K-way merge

Pattern : 0/1 Knapsack (Dynamic Programming)

Pattern: Topological Sort (Graph)

Miscellaneous

Conclusions

Top 'K' Frequent Numbers (medium)

Problem Statement

Try it yourself

Solution