[LeetCode] Merge Intervals

/**
* 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 compare(const Interval &inv1, const Interval &inv2) {
return inv1.start < inv2.start;
}

class Solution {
public:
vector<Interval> merge(vector<Interval> &intervals) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
vector<Interval> ret;

if (intervals.empty()) return ret;

sort(intervals.begin(), intervals.end(), compare);

ret.push_back(intervals[0]);

for (int i = 1; i < intervals.size(); i++) {
if (ret.back().end >= intervals[i].start)
ret.back().end = max(ret.back().end, intervals[i].end);
else
ret.push_back(intervals[i]);
}

return ret;
}
};