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56. Merge Intervals

Medium

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.

Example 1:

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] overlaps, merge them into [1,6].

Example 2:

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

Output: [[1,5]]

Explanation: Intervals [1,4] and [4,5] are considered overlapping.

Constraints:

• 1 <= intervals.length <= 104
• intervals[i].length == 2
• 0 <= starti <= endi <= 104

Solution

public class Solution {
    public int[][] Merge(int[][] intervals) {
        Array.Sort(intervals, (a, b) => a[0] - b[0]);
        for (int i = 1; i < intervals.Length; i++) {
            if (intervals[i][0] <= intervals[i - 1][1]) {
                intervals[i][0] = intervals[i - 1][0];
                intervals[i][1] = Math.Max(intervals[i - 1][1], intervals[i][1]);
                intervals[i - 1][0] = -1;
            }
        }
        return intervals.Where(obj => obj[0] != -1).ToArray();
    }
}

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