LeetCode--Insert Interval

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).

You may assume that the intervals were initially sorted according to their start times.

Example 1:
Given intervals [1,3],[6,9], insert and merge [2,5] in as [1,5],[6,9].

Example 2:
Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16].

This is because the new interval [4,9] overlaps with [3,5],[6,7],[8,10].

/** * 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)     {        vector<Interval>& in = intervals;        heap_sort(in);        int n = in.size();        vector<Interval> res;        bool flag = false;        for(int i=0; i<n; i++)        {            if(in[i].start > newInterval.start && flag==false)            {                res.push_back(newInterval);                flag = true;            }            res.push_back(in[i]);        }        if(!flag)            res.push_back(newInterval);        return merge(res);    }    vector<Interval> merge(vector<Interval> &intervals)     {        vector<Interval> res;        vector<Interval>& in = intervals;        int n = in.size();        if(n == 0)            return res;        if(n == 1)            return in;        Interval temp = in[0];        for(int i=1; i<n; i++)        {            if(temp.end < in[i].start)            {                res.push_back(temp);                temp = in[i];            }            else            {                int start = temp.start<in[i].start? temp.start:in[i].start;                int end = temp.end>in[i].end? temp.end:in[i].end;                temp.start = start;                temp.end = end;            }        }        res.push_back(temp);        return res;    }    void swap(vector<Interval>& in, int i, int j)    {        int s = in[i].start;        int e = in[i].end;        in[i].start = in[j].start;        in[i].end = in[j].end;        in[j].start = s;        in[j].end = e;    }    void sink(vector<Interval>& in, int loc, int end)    {        while(loc<end)        {            int k =2*loc+1;            if(k>end)                return;            if(k<end && in[k].start<in[k+1].start)                k++;            if(in[loc].start>in[k].start)                return;            swap(in,loc,k);            loc = k;        }    }    void heap_sort(vector<Interval>& in)    {        int n = in.size()-1;        for(int i=(n-1)/2; i>=0; i--)            sink(in,i,n);        while(n>0)        {            swap(in,0,n);            n--;            sink(in,0,n);        }    }};