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].

区间合并，分为三种情况

/**
 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };
 */
class Solution{
public:
    static bool compare(Interval& a,Interval& b){
        return a.start < b.start;
    }
    vector<Interval> merge(vector<Interval>& intervals){
        vector<Interval> res;
        int size = intervals.size();
        if(size < 2) return intervals;
        sort(intervals.begin(),intervals.end(),compare);
        Interval tmpInterval = intervals[0];
        for(int i=1;i<size;i++){
            if(tmpInterval.end < intervals[i].start){
                res.push_back(tmpInterval);
                tmpInterval = intervals[i];
            }else if(tmpInterval.start > intervals[i].end){
                res.push_back(intervals[i]);
            }else{
                tmpInterval.start = min(tmpInterval.start,intervals[i].start);
                tmpInterval.end = max(tmpInterval.end,intervals[i].end);
            }
        }
        res.push_back(tmpInterval);
        return res;
    }
};