[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].

/**
 * 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> merge(vector<Interval> &intervals) {
        int pos = 0, cnt = 0;
        sort(intervals.begin(), intervals.end(), cmp);
        for (int i = 1; i < intervals.size(); ++i) {
            if (intervals[pos].end >= intervals[i].start) {
                    ++cnt;
                    if (intervals[pos].end <= intervals[i].end) {
                        intervals[pos].end = intervals[i].end;
                    }
            } else {
                ++pos;
                intervals[pos].start = intervals[i].start;
                intervals[pos].end = intervals[i].end;
            }
        }
        intervals.resize(intervals.size()-cnt);
        return intervals;
    }
};