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].

bool CompInterval(const Interval& pl, const Interval& pr)
{
	return pl.start < pr.start;
}
class Solution {
public:
	vector<Interval> merge(vector<Interval>& intervals) {
		if (intervals.empty() || intervals.size() == 1)
			return intervals;
		sort(intervals.begin(), intervals.end(), CompInterval);
		int k = 0;
		while (k + 1<intervals.size())
		{
			while (k + 1<intervals.size() && intervals[k].end < intervals[k + 1].start)
				k++;
			if (k + 1 == intervals.size())
				return intervals;
			int end = intervals[k].end >= intervals[k + 1].end
				? intervals[k].end : intervals[k + 1].end;
			int kk = k;
			while (kk + 1 < intervals.size() && end >= intervals[kk + 1].start)
			{
				if (intervals[kk + 1].end > end)
					end = intervals[kk + 1].end;
				kk++;
			}
			intervals[k].end = end;
			intervals.erase(intervals.begin() + k + 1, intervals.begin() + kk + 1);
			k++;
		}
		return intervals;
	}
};

accepted