Submission
/**
* 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:
static bool comp(Interval& a, Interval& b) {return a.start < b.start;}
vector<Interval> merge(vector<Interval>& intervals) {
if(intervals.empty()) return vector<Interval>();
vector<Interval> result;
sort(intervals.begin(), intervals.end(), comp);
Interval last = Interval(intervals[0].start, intervals[0].end);
for(int i = 1; i < intervals.size(); i++) {
if(intervals[i].start <= last.end) {
if(intervals[i].end > last.end) {
last.end = intervals[i].end;
}
} else {
result.push_back(last);
last.start = intervals[i].start;
last.end = intervals[i].end;
}
}
result.push_back(last);
return result;
}
};
Time
13ms
Explanation
First sort the array according to interval's start value in ascending order. Iterate starts at the first interval, and keep a reference of the last checked/merged interval. For each new interval, check if it should be merged; if not, add the current last interval to result.
Notes
- c++ vector's push_back function makes a copy of the argument.
- left reference & cannot be reassigned.
