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| id | title | toc_max_heading_level |
|---|---|---|
| interval | Interval | 2 |
Introduction
Interval questions are a subset of array questions where you are given an array of two-element arrays (an interval) and the two values represent a start and an end value. Interval questions are considered part of the array family but they involve some common techniques hence they are extracted out to this special section of their own.
An example interval array: [[1, 2], [4, 7]].
Interval questions can be tricky to those who have not tried them before because of the sheer number of cases to consider when they overlap.
Corner cases
- Single interval
- Non-overlapping intervals
- An interval totally consumed within another interval
- Duplicate intervals
Things to look out for during interviews
- Do clarify with the interviewer whether
[1, 2]and[2, 3]are considered overlapping intervals as it affects how you will write your equality checks.
Techniques
Sort the array of intervals by its starting point
A common routine for interval questions is to sort the array of intervals by each interval's starting value. This step is crucial to solving the Merge Intervals question.
Checking if two intervals overlap
Be familiar with writing code to check if two intervals overlap.
def is_overlap(a, b):
return a[0] < b[1] and b[0] < a[1]
Merging two intervals
def merge_overlapping_intervals(a, b):
return [min(a[0], b[0]), max(a[1], b[1])]
Recommended questions
- Merge Intervals
- Insert Interval
- Non-overlapping Intervals
- Meeting Rooms (LeetCode Premium)
- Meeting Rooms II (LeetCode Premium)
Recommended courses
import AlgorithmCourses from '../_courses/AlgorithmCourses.md'