Merge Intervals: coding question

Problem

You get a list intervals in no special order. Each item [start, end] is one interval.

Two intervals overlap when they share at least one point. For example, [2, 5] and [5, 7] overlap at the point 5.

Merge the intervals that overlap, and continue until no two intervals overlap. When you merge intervals, you replace them with one interval from their smallest start to their largest end.

Return the result in ascending order of start.

Example 1

Input:: intervals = [[8,10],[1,3],[2,5],[12,14],[9,11]]
Output:: [[1,5],[8,11],[12,14]]
Explanation:: The intervals [1, 3] and [2, 5] merge into [1, 5]. The intervals [8, 10] and [9, 11] merge into [8, 11].

Example 2

Input:: intervals = [[3,4],[4,9]]
Output:: [[3,9]]
Explanation:: The two intervals share the point 4, so they merge.

Example 3

Input:: intervals = [[1,10],[2,3],[4,5]]
Output:: [[1,10]]
Explanation:: The first interval contains the other two intervals.

Constraints

1 <= intervals.length <= 10^4
intervals[i].length == 2
0 <= start <= end <= 10^4

SysRound wrote this statement. A reference solution checks every example.

Continue with questions that share topics or the same question type.

Sort Colors
Coding · Array · Bubble Sort · Quicksort
Accounts Merge
Coding · Array · Breadth-First Search · Depth-First Search
Merge Sorted Array
Coding · Array · Sorting · Two Pointers
Non-overlapping Intervals
Coding · Array · Dynamic Programming · Greedy

Sources · 2 references

These records explain where the question appears. A company tag or candidate report does not guarantee a future interview question.

Hello Interview · 12 records

Amazon
Leetcode 56. Merge Intervals
Reported Sep 30, 2026 · 9 source reports
JUNIOR, MID_LEVEL, SENIOR
Source snapshot: Nov 12, 2026
View source
Antithesis
Leetcode 56. Merge Intervals
Reported Nov 19, 2025 · 1 source report
SENIOR
Source snapshot: Nov 12, 2026
View source
Apple
Leetcode 56. Merge Intervals
Reported Oct 1, 2026 · 3 source reports
MID_LEVEL, SENIOR
Source snapshot: Nov 12, 2026
View source
Atlassian
Leetcode 56. Merge Intervals
Reported Oct 16, 2026 · 2 source reports
PRINCIPAL, STAFF
Source snapshot: Nov 12, 2026
View source

Problem

You get a list intervals in no special order. Each item [start, end] is one interval.

Two intervals overlap when they share at least one point. For example, [2, 5] and [5, 7] overlap at the point 5.

Merge the intervals that overlap, and continue until no two intervals overlap. When you merge intervals, you replace them with one interval from their smallest start to their largest end.

Return the result in ascending order of start.

Example 1

Input:: intervals = [[8,10],[1,3],[2,5],[12,14],[9,11]]
Output:: [[1,5],[8,11],[12,14]]
Explanation:: The intervals [1, 3] and [2, 5] merge into [1, 5]. The intervals [8, 10] and [9, 11] merge into [8, 11].

Example 2

Input:: intervals = [[3,4],[4,9]]
Output:: [[3,9]]
Explanation:: The two intervals share the point 4, so they merge.

Example 3

Input:: intervals = [[1,10],[2,3],[4,5]]
Output:: [[1,10]]
Explanation:: The first interval contains the other two intervals.

Constraints

1 <= intervals.length <= 10^4
intervals[i].length == 2
0 <= start <= end <= 10^4

SysRound wrote this statement. A reference solution checks every example.

Merge Intervals

Problem

Example 1

Example 2

Example 3

Constraints

Related questions

Merge Intervals

Problem

Example 1

Example 2

Example 3

Constraints

Related questions