LeetCode

The problem Given an array of meeting time intervals intervals where intervals[i] = [starti, endi], return the minimum number of conference rooms required. Examples Input: intervals = [[0,30],[5,10],[15,20]] Output: 2 Input: intervals = [[7,10],[2,4]] Output: 1 Constraints 1 <= intervals.length <= 10^4 0 <= starti < endi <= 10^6 Explanation Before jumping to the code, we are going to sort the input because it’s not sorted by default. Sorting Solution func minMeetingRooms(_ intervals: [[Int]]) -> Int { let start = intervals.map({ $0[0] }).sorted() let end = intervals.map({ $0[1] }).sorted() var res = 0 var count = 0 var s = 0 var e = 0 let n = intervals.count while s < n { if start[s] < end[e] { s += 1 count += 1 } else { e += 1 count -= 1 } res = max(res, count) } return res } Explanation We can visualize input with intervals = [[0,30],[5,10],[15,20]] like this: ...

The problem Given an array of meeting time intervals where intervals[i] = [starti, endi], determine if a person could attend all meetings. Examples Input: intervals = [[0,30],[5,10],[15,20]] Output: false Input: intervals = [[7,10],[2,4]] Output: true Constraints 0 <= intervals.length <= 10^4 intervals[i].length == 2 0 <= starti < endi <= 10^6 Explanation Before we dive into coding, let’s look at base cases in which intervals are not overlapping. ...

The problem Given an array of intervals where intervals[i] = [starti, endi], return the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping. Note that intervals which only touch at a point are non-overlapping. For example, [1, 2] and [2, 3] are non-overlapping. Examples Input: intervals = [[1,2],[2,3],[3,4],[1,3]] Output: 1 Explanation: [1,3] can be removed and the rest of the intervals are non-overlapping. Input: intervals = [[1,2],[1,2],[1,2]] Output: 2 Explanation: You need to remove two [1,2] to make the rest of the intervals non-overlapping. Input: intervals = [[1,2],[2,3]] Output: 0 Explanation: You don't need to remove any of the intervals since they're already non-overlapping. Constraints 1 <= intervals.length <= 10^5 intervals[i].length == 2 -5 * 10^4 <= starti < endi <= 5 * 10^4 Explanation Before we dive into coding, let’s figure out the definition of overlapping intervals for this problem. ...

The problem Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input. Examples Input: intervals = [[1,3],[2,6],[8,10],[15,18]] Output: [[1,6],[8,10],[15,18]] Explanation: Since intervals [1,3] and [2,6] overlap, merge them into [1,6]. Input: intervals = [[1,4],[4,5]] Output: [[1,5]] Explanation: Intervals [1,4] and [4,5] are considered overlapping. Constraints 1 <= intervals.length <= 10^4 intervals[i].length == 2 0 <= starti <= endi <= 10^4 Explanation Let’s look at examples and figure out our base cases for intervals that are considered overlapping. ...

The problem You are given an array of non-overlapping intervals intervals where intervals[i] = [starti, endi] represents the start and the end of the ith interval, and intervals is sorted in ascending order by starti. You are also given an interval newInterval = [start, end] that represents the start and end of another interval. Insert newInterval into intervals such that intervals is still sorted in ascending order by starti and intervals still does not have any overlapping intervals (merge overlapping intervals if necessary). ...