What is the Find K Closest Elements pattern?

The Find K Closest Elements is a common coding interview pattern in Heap Priority Queue problems. It provides a structured approach to solving related algorithm challenges efficiently.

When should I use Find K Closest Elements?

Use the Find K Closest Elements pattern when you encounter problems matching its characteristics. Check the "When to Use" and "Clues" sections in the lesson for specific indicators.

Is Find K Closest Elements asked in FAANG interviews?

Yes, Find K Closest Elements is an essential pattern commonly tested in FAANG and top tech company technical interviews.

Heap / Priority Queue

Medium

Find K Closest Elements

Find k closest integers to a given value x.

10 min read

Solve on LeetCode

Problem Understanding

Given a sorted integer array arr, two integers k and x, return the k closest integers to x.

If |a - x| == |b - x|, the smaller number is chosen. The internal array must be sorted.

Example:

Input: arr = [1,2,3,4,5], k = 4, x = 3
Output: [1,2,3,4]

Algorithm Strategy

Approach 1: Max-Heap (Standard Top-K)
Similar to previous problems, maintain a Max-Heap of size K.

Priority is distance |val - x|.
Pop the element with the largest distance if size > K.

Approach 2: Two Pointers (Optimal for Sorted Input)
Since the array is sorted, the K closest elements will be a contiguous subarray.

Use Binary Search to find the closest element to x.
Expand Left and Right pointers to collect K neighbours.

Interactive Visualization

Step 1 / 1

Empty Heap

Initializing...

Custom Input

K Value

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