Intervals/Merge IntervalsMedium

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Merge Intervals

Intervals·Medium

Given an array of intervals where intervals[i] = [start_i, end_i], merge all overlapping intervals and return an array of the non-overlapping intervals that cover all the intervals in the input.

Intervals that touch at a point (e.g. [1,4] and [4,5]) should be merged into a single interval ([1,5]). The output must be sorted by start ascending.

Examples

Input: intervals = [[1,3],[2,6],[8,10],[15,18]]

Output: [[1,6],[8,10],[15,18]]

Input: intervals = [[1,4],[4,5]]

Output: [[1,5]]

End-touching intervals are merged.

Input: intervals = []

Output: []

Constraints

1 <= intervals.length <= 10^4
intervals[i].length == 2
0 <= start_i <= end_i <= 10^4

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Tests

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Passed32 ms

First attempt — retry to track metric movement here.

Your approach

Pattern:Intervals
Time:O(N)
Space:O(1)

Complete approach — pattern and complexity both named.

Coach

What you got right

You correctly matched the sorted input requirement and implemented a linear-time scan using two pointers.

Where it diverged

No divergence detected. The code correctly aligns with the stated approach.

Next attempt: focus on

Try solving related sliding window problems to build familiarity with two-pointer variants.

Signals

No signals fired — clean run, you stayed in flow.