LeetCode: Merge Intervals

出了个小问题，但是这问题又那么蛋疼。。bool cmp这函数不能放在solution里，我也不知道为什么，放外面就能过

 1 /**
 2  * Definition for an interval.
 3  * struct Interval {
 4  *     int start;
 5  *     int end;
 6  *     Interval() : start(0), end(0) {}
 7  *     Interval(int s, int e) : start(s), end(e) {}
 8  * };
 9  */
10 bool cmp(const Interval a, const Interval b) {
11     if (a.start == b.start) return a.end < b.end;
12     return a.start < b.start;
13 }
14 class Solution {
15 public:
16     vector<Interval> merge(vector<Interval> &intervals) {
17         // Start typing your C/C++ solution below
18         // DO NOT write int main() function
19         sort(intervals.begin(), intervals.end(), cmp);
20         vector<Interval> ret;
21         for (int i = 0; i < intervals.size(); i++) {
22             if (!ret.size() || intervals[i].start > ret.back().end) ret.push_back(intervals[i]);
23             else ret.back().end = max(ret.back().end, intervals[i].end);
24         }
25         return ret;
26     }
27 };

C#:注意两个问题，1，IList并没有sort函数，因此要先转换成List，2，intervals的sort函数的排序有两种方法，注释里的也可以用，随便选，这里sort里的必须是Comparison<Interval>或者IComparer<Interval>的，都必须是静态（static）的

 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 public class Solution {
11     class StartEndComparer : IComparer<Interval>
12     {
13         public static StartEndComparer Default = new StartEndComparer();
14         public int Compare(Interval v1, Interval v2)
15         {
16             if (v1.start == v2.start) return v1.end - v2.end;
17             return v1.start - v2.start;
18         }
19     }
20     public class IntervalComparison
21     {
22         public static int StartEnd(Interval v1, Interval v2)
23         {
24             if (v1.start == v2.start) return v1.end - v2.end;
25             return v1.start - v2.start;
26         }
27     }
28     public List<Interval> Merge(IList<Interval> intervals) {
29         
30         List<Interval> intervalsCopy = new List<Interval>(intervals.ToArray());
31         Comparison<Interval> StartEndComparison = new Comparison<Interval>(IntervalComparison.StartEnd);
32         intervalsCopy.Sort(StartEndComparison);
33         //intervalsCopy.Sort(StartEndComparer.Default);
34         List<Interval> ans = new List<Interval>();
35         for (int i = 0; i < intervals.Count; i++) {
36             if (ans.Count == 0 || intervalsCopy[i].start > ans[ans.Count-1].end) ans.Add(intervalsCopy[i]);
37             else ans[ans.Count-1].end = Math.Max(ans[ans.Count-1].end, intervalsCopy[i].end);
38         }
39         return ans;
40     }
41 }

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