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How do you merge overlapping intervals?

Q: How do you merge overlapping intervals?

**Intuition.** Sort the intervals by **start** time. Then sweep left to right: if the next interval starts before (or when) the current one ends, they overlap — extend the end. Otherwise there's a gap, so close out the current interval and begin a new one. [1,3] [2,6] [8,10] → [1,6] [8,10] [1,3] <rect x="80" y="44" width="160" height="18" rx="4" fill="

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Explain merge intervals.

intervalssorting

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Sort then sweep

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def merge(intervals):
    intervals.sort(key=lambda x: x[0])
    merged = [intervals[0]]
    for start, end in intervals[1:]:
        if start <= merged[-1][1]:           # overlap
            merged[-1][1] = max(merged[-1][1], end)
        else:
            merged.append([start, end])
    return merged


# --- demo ---
print(merge([[1, 3], [2, 6], [8, 10], [15, 18]]))   # [[1, 6], [8, 10], [15, 18]]

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