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Interval List Intersections

Explore how to determine the intersection of two closed interval lists, focusing on understanding interval overlap and efficiently solving interval intersection problems. This lesson helps you build skills to approach and implement solutions for interval challenges commonly seen in coding interviews.

Statement

Given two lists of closed intervalsA closed interval [start, end] (with start <= end) includes all real numbers x such that start <= x <= end., intervalListA and intervalListB, return the intersection of the two interval lists.

Each interval in the lists has its own start and end time and is represented as [start, end]. Specifically:

  • intervalListA[i] = [starti, endi]

  • intervalListB[j] = [startj, endj]

The intersection of two closed intervals i and j is either:

  • An empty set, if they do not overlap, or

  • A closed interval [max(starti, startj), min(endi, endj)] if they do overlap.

Also, each list of intervals is pairwise disjoint and in sorted order.

Constraints:

  • 00 \leq intervalListA.length, intervalListB.length 1000\leq 1000

  • intervalListA.length ++ intervalListB.length >=1>=1

  • 00 \leq starti << endi 109\leq 10^9

  • endi << starti + 1

  • 00 \leq startj << endj 109\leq 10^9

  • endj << start[j + 1]

Examples

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Understand the problem

Let’s take a moment to make sure you’ve correctly understood the problem. The quiz below helps you check if you’re solving the correct problem:

Interval List Intersections

1.

From the following interval lists, find their intersecting intervals.

First list = [[2, 6], [7, 9], [10, 13], [14, 19], [20, 24]]

Second list = [[1, 4], [6, 8], [15, 18]]

A.

[[1, 4], [6, 8], [13, 18]]

B.

[[2, 4], [6, 6], [7, 8], [15, 18]]

C.

[[2, 4], [6, 8], [15, 18]]


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Figure it out!

We have a game for you to play. Rearrange the logical building blocks to develop a clearer understanding of how to solve this problem.

Sequence - Vertical
Drag and drop the cards to rearrange them in the correct sequence.

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Try it yourself

Implement your solution in main.js in the following coding playground. You will need the provided supporting code to implement your solution.

JavaScript
usercode > main.js
function intervalsIntersection(intervalListA, intervalListB) {
// Replace this placeholder return statement with your code
return [];
}
export { intervalsIntersection };
Interval List Intersections