[LeetCode] Insert Interval

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).

You may assume that the intervals were initially sorted according to their start times.

Example 1:
Given intervals [1,3],[6,9], insert and merge [2,5] in as [1,5],[6,9].

Example 2:
Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16].

This is because the new interval [4,9] overlaps with [3,5],[6,7],[8,10].

/**
 * 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)
{
    return a.start < b.start;
}
class Solution {
public:
    vector<Interval> insert(vector<Interval> &intervals, Interval newInterval) {
        intervals.push_back(newInterval);
        return merge(intervals);
    }
    vector<Interval> merge(vector<Interval> &intervals) {
        sort(intervals.begin(), intervals.end(), cmp);
        vector<Interval> res;
        if(intervals.empty())     return res;
        vector<Interval>::iterator it = intervals.begin();
        Interval temp = *it++;
        if(it == intervals.end())
            res.push_back(temp);
        else
        {
            while(it != intervals.end())
            {
                while((*it).start <= temp.end && it != intervals.end())
                {
                    temp.end = max(temp.end, (*it).end);
                    ++it;
                }
                res.push_back(temp);
                temp = *it;
            }
        }
        return res;
    }
};