56 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].

Solution

/**
 * 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> insert(vector<Interval>& intervals, Interval newInterval) {
        int n = intervals.size();
        auto it = intervals.begin();
        while ( it != intervals.end() ) {
            int s = it->start, e = it->end;
            if ( newInterval.end < s or e < newInterval.start ) {it++; continue;}
            newInterval.start = min(s, newInterval.start);
            newInterval.end = max(e, newInterval.end);
            it = intervals.erase(it);
        }
        intervals.push_back(newInterval);
        return intervals;
    }
    vector<Interval> merge(vector<Interval>& intervals) {
        int n = intervals.size();
        if ( n <= 1 ) return intervals;
        vector<Interval> res(1, intervals[0]);
        for ( int i = 1; i <= n-1; i++ ) res = insert(res, intervals[i]);
        return res;
    }
};

Notes
Insert intervals one by one.