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

/**
 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };
 */
bool cmp(const Interval a, const Interval b) {
    if (a.start == b.start) return a.end < b.end;
    return a.start < b.start;
}
class Solution {
public:
    vector<Interval> merge(vector<Interval> &intervals) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        sort(intervals.begin(), intervals.end(), cmp);
        vector<Interval> ret;
        for (int i = 0; i < intervals.size(); i++) {
            if (!ret.size() || intervals[i].start > ret.back().end) ret.push_back(intervals[i]);
            else ret.back().end = max(ret.back().end, intervals[i].end);
        }
        return ret;
    }
};

 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

/**
 * 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 Solution {
    class StartEndComparer : IComparer<Interval>
    {
        public static StartEndComparer Default = new StartEndComparer();
        public int Compare(Interval v1, Interval v2)
        {
            if (v1.start == v2.start) return v1.end - v2.end;
            return v1.start - v2.start;
        }
    }
    public class IntervalComparison
    {
        public static int StartEnd(Interval v1, Interval v2)
        {
            if (v1.start == v2.start) return v1.end - v2.end;
            return v1.start - v2.start;
        }
    }
    public List<Interval> Merge(IList<Interval> intervals) {
        
        List<Interval> intervalsCopy = new List<Interval>(intervals.ToArray());
        Comparison<Interval> StartEndComparison = new Comparison<Interval>(IntervalComparison.StartEnd);
        intervalsCopy.Sort(StartEndComparison);
        //intervalsCopy.Sort(StartEndComparer.Default);
        List<Interval> ans = new List<Interval>();
        for (int i = 0; i < intervals.Count; i++) {
            if (ans.Count == 0 || intervalsCopy[i].start > ans[ans.Count-1].end) ans.Add(intervalsCopy[i]);
            else ans[ans.Count-1].end = Math.Max(ans[ans.Count-1].end, intervalsCopy[i].end);
        }
        return ans;
    }
}