LeetCode [Sort]: Merge Intervals, leetcodemerge

LeetCode [Sort]: Merge Intervals, leetcodemerge

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].

This question is actually not difficult. You only need to understand the various situations and use the insert sort method. My C ++ code implementation is as follows:

    vector<Interval> merge(vector<Interval> &intervals) {        vector<Interval> mergeIntervals;        for (auto interval : intervals) {            int i;            for (i = 0; i < mergeIntervals.size(); ++i) {                if (interval.end < mergeIntervals[i].start) {                    mergeIntervals.insert(mergeIntervals.begin() + i, interval);                    break;                }                else if (interval.start <= mergeIntervals[i].end) {                    mergeIntervals[i].start = min(interval.start, mergeIntervals[i].start);                    if (interval.end > mergeIntervals[i].end) {                        while (i + 1 < mergeIntervals.size() && interval.end >= mergeIntervals[i + 1].start) {                            mergeIntervals[i].end = mergeIntervals[i + 1].end;                            mergeIntervals.erase(mergeIntervals.begin() + i + 1);                        }                        mergeIntervals[i].end = max(interval.end, mergeIntervals[i].end);                    }                    break;                }            }            if (i == mergeIntervals.size())                mergeIntervals.push_back(interval);        }        return mergeIntervals;    }

Shows the time performance:

In addition, on Discuss, we see a solution (https://oj.leetcode.com/discuss/13953/a-simple-java-solution): First sort all input intervals by start using the sort function, and then insert them one by one. This method is also worth learning.