[LeetCode]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]

.

思路：首先对元素进行排序，按照start升序排序。然后依次合并。

但是代码运行时间略长600ms。暂时没想到更好的解法。

LeetCode Source

代码如下：

/**
* 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:
vector<Interval> merge(vector<Interval>& intervals) {
if(intervals.size()==0)
return intervals;
sort(intervals.begin(),intervals.end(),
[](const Interval&a,const Interval&b){return a.start<b.start;});
vector<Interval> ret;
ret.push_back(intervals[0]);
for(auto i=1;i<intervals.size();++i){
Interval &temp = ret.back();
if(temp.end>=intervals[i].start){
if(temp.end<=intervals[i].end)
temp.end = intervals[i].end;
}
else{
ret.push_back(intervals[i]);
}
}
return ret;
}
};