[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 };