Leetcode 56: Merge Intervals

Posted 2020-10-13 Keep walking

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].

 

 1 /**
 2  * Definition for an interval.
 3  * public class Interval {
 4  *     public int start;
 5  *     public int end;
 6  *     public Interval() { start = 0; end = 0; }
 7  *     public Interval(int s, int e) { start = s; end = e; }
 8  * }
 9  */
10 
11 public class IntervalComparer: IComparer<Interval>
12 {
13     public int Compare(Interval x, Interval y)
14     {
15         return x.start != y.start ? x.start - y.start : x.end - y.end;
16     }
17 }
18     
19 public class Solution {
20     public IList<Interval> Merge(IList<Interval> intervals) {
21         if (intervals.Count < 2) return intervals;
22         
23         var list = intervals.ToList();
24         
25         list.Sort(new IntervalComparer());
26         
27         var result = new List<Interval>();
28         
29         for (int i = 0; i < list.Count; i++)
30         {
31             if (i == 0 || list[i].start > result[result.Count - 1].end)
32             {
33                 result.Add(list[i]);
34             }
35             else
36             {
37                 result[result.Count - 1].end = Math.Max(result[result.Count - 1].end, list[i].end);
38             }
39         }
40         
41         return result;
42     }
43 }