Remove Covered Intervals

MediumIntervalsgreedy

Solve this the way you would in the interview: out loud, on a timer, with an AI interviewer asking follow-ups while you code. You get a scored report at the end.

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Problem

You are given a list of distinct intervals, where intervals[i] = [l_i, r_i]. Interval [a, b] is *covered* by interval [c, d] when c <= a and b <= d (and the two intervals are different entries). Remove every interval that is covered by some other interval in the list, and return how many intervals remain.

Examples

Input: intervals = [[1,4],[3,6],[2,8]]
Output: 2
`[3,6]` lies inside `[2,8]`, so it is removed.
Input: intervals = [[1,4],[2,3]]
Output: 1
`[2,3]` lies inside `[1,4]`.

Constraints

  • 1 <= intervals.length <= 1000
  • intervals[i].length == 2
  • 0 <= l_i < r_i <= 10^5
  • All intervals are distinct

What the interviewer grades

A correct solution is one of five scores. The report also grades problem understanding (did you clarify inputs and edge cases before coding), problem solving, communication while you work, code quality, and testing. See a sample report, or read up on the pattern in the lessons.

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