Merge Intervals
Merge all overlapping intervals.
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Lesson notes
Try it before you watch
Restate the problem in your own words, list the edge cases, and sketch a solution with its running time. Then play the video and compare.
Reveal the key idea
Sort intervals by start. Extend the last merged interval when the next one overlaps it; otherwise start a new merged interval.
Pattern: Greedy & intervals. Make the locally best choice, usually after sorting, and argue why it never hurts later.
Complexity
| Measure | Bound |
|---|---|
| Time | O(n log n) |
| Extra space | O(n) |
Walkthroughs often start from a simpler approach first; aim to reach these bounds. New to Big-O? Read understanding algorithmic complexity.