Count connected components in array
Last updated: September 16, 2025
Quick Overview
Given an array of integers, count the number of connected components in the array where a connected component is defined as a subset of elements that are consecutive integers. The input will be an array of integers and the output should be the total number of connected components found in the array.
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Given an array of integers, count the number of connected components in the array where a connected component is defined as a subset of elements that are consecutive integers. The input will be an array of integers and the output should be the total number of connected components found in the array.
This coding problem is frequently asked during Phone Screen at Pinterest. The interviewer is testing your ability to translate a problem into clean, working code while discussing time and space complexity. Pinterest expects candidates to write production-quality code, not just solve the puzzle.
What the Interviewer Expects
- Identify the correct data structure and algorithm for the problem
- Write clean, bug-free code with proper variable naming
- Analyze time and space complexity correctly
- Handle basic edge cases (empty input, single element)
- Communicate your thought process while coding
Key Topics to Cover
How to Approach This
- Clarify input constraints and edge cases before writing code.
- Walk through your approach verbally and confirm with the interviewer before coding.
- Start with a brute force solution, then optimize. Mention time and space complexity.
- Test your solution with examples, including edge cases like empty input or duplicates.
- Consider common patterns: sliding window, two pointers, hash map, BFS/DFS, dynamic programming.
Possible Follow-up Questions
- What if the input doesn't fit in memory?
- Can you solve this in a single pass?
- How would you parallelize this solution?
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Problem Analysis
To solve the problem of counting connected components in an array, we can identify that a connected component consists of elements that are consecutive integers. Therefore, the task can be visualized ...
Approach
- Sort the Array: First, we sort the input array, which allows us to arrange the integers in increasing order. For example, if we have the array [4, 1, 3, 2, 6], after sorting, it becomes [1, 2, ...
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