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$ curl repovive.com/roadmaps/data-structures/interval-trees/non-overlapping-solution

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$ curl repovive.com/roadmaps/data-structures/interval-trees/non-overlapping-solution

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Non-overlapping Solution - Interval Trees | Data Structures | Repovive

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Data Structures19 sections · 729 units49h total

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Non-overlapping Solution

Greedy removal

Find max non-overlapping, then removals = total - max.

function eraseOverlapIntervals(intervals)
    sort intervals by end time
    kept := 0
    lastEnd := -infinity

    for interval in intervals
        if interval.start >= lastEnd then
            kept := kept + 1
            lastEnd := interval.end

    return length(intervals) - kept

Alternatively, count how many times we skip an interval:

When a new interval overlaps the previous, remove the one ending later (keep the one ending earlier to maximize future options).

Time: $O(n \log n)$ . Space: $O(1)$ .