Leetcode 56: Merge Intervals

Given a collection of intervals, merge all overlapping intervals.

For example,
Given [1,3],[2,6],[8,10],[15,18],
return [1,6],[8,10],[15,18].

 

/**
 * Definition for an interval.
 * public class Interval {
 *     public int start;
 *     public int end;
 *     public Interval() { start = 0; end = 0; }
 *     public Interval(int s, int e) { start = s; end = e; }
 * }
 */

public class IntervalComparer: IComparer<Interval>
{
    public int Compare(Interval x, Interval y)
    {
        return x.start != y.start ? x.start - y.start : x.end - y.end;
    }
}
    
public class Solution {
    public IList<Interval> Merge(IList<Interval> intervals) {
        if (intervals.Count < 2) return intervals;
        
        var list = intervals.ToList();
        
        list.Sort(new IntervalComparer());
        
        var result = new List<Interval>();
        
        for (int i = 0; i < list.Count; i++)
        {
            if (i == 0 || list[i].start > result[result.Count - 1].end)
            {
                result.Add(list[i]);
            }
            else
            {
                result[result.Count - 1].end = Math.Max(result[result.Count - 1].end, list[i].end);
            }
        }
        
        return result;
    }
}