Solution.cs

public class Solution {
    public int[][] Insert(int[][] intervals, int[] newInterval) {
        int[][] newIntervals = new int[intervals.Length + 1][];
        for (int i = 0; i < intervals.Length; ++i) {
            newIntervals[i] = intervals[i];
        }
        newIntervals[intervals.Length] = newInterval;
        return Merge(newIntervals);
    }

    public int[][] Merge(int[][] intervals) {
        intervals = intervals.OrderBy(a => a[0]).ToArray();
        var ans = new List<int[]>();
        ans.Add(intervals[0]);
        for (int i = 1; i < intervals.Length; ++i) {
            if (ans[ans.Count - 1][1] < intervals[i][0]) {
                ans.Add(intervals[i]);
            } else {
                ans[ans.Count - 1][1] = Math.Max(ans[ans.Count - 1][1], intervals[i][1]);
            }
        }
        return ans.ToArray();
    }
}