[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].

 1 /**

 2  * Definition for an interval.

 3  * struct Interval {

 4  *     int start;

 5  *     int end;

 6  *     Interval() : start(0), end(0) {}

 7  *     Interval(int s, int e) : start(s), end(e) {}

 8  * };

 9  */

10  

11 bool cmp(const Interval &a, const Interval &b) {

12     return a.start < b.start;

13 }

14     

15 class Solution {

16 public:

17     vector<Interval> merge(vector<Interval> &intervals) {

18         int pos = 0, cnt = 0;

19         sort(intervals.begin(), intervals.end(), cmp);

20         for (int i = 1; i < intervals.size(); ++i) {

21             if (intervals[pos].end >= intervals[i].start) {

22                     ++cnt;

23                     if (intervals[pos].end <= intervals[i].end) {

24                         intervals[pos].end = intervals[i].end;

25                     }

26             } else {

27                 ++pos;

28                 intervals[pos].start = intervals[i].start;

29                 intervals[pos].end = intervals[i].end;

30             }

31         }

32         intervals.resize(intervals.size()-cnt);

33         return intervals;

34     }

35 };