LeetCode | 57. 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].

题目大意：给定一些区间（已经按start升序排列），和一个要你插入的区间，插入这个目标区间，并做相应的合并。
麻烦之处：要注意的细节比较多。比如将区间插入空的区间集合；插入之后做完合并之后还要保持start值有序等。总体难度评级为medium吧，应该算不上hard。

// 16 ms/** * 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 cmp(Interval a,Interval b)    {        return a.start<b.start;    }    vector<Interval> insert(vector<Interval>& intervals, Interval newInterval) {        int flag = 0;       //判断该区间是否放入        int n = intervals.size();        vector<Interval> res;        if(n == 0)        {            res.push_back(newInterval);            return res;        }        if(newInterval.end < intervals[0].start)        //放在最左边，因为答案要求 x 坐标有序。。。        {            flag = 1;            res.push_back(newInterval);        }        for(int i=0;i<n;i++)        {            if(intervals[i].end < newInterval.start || intervals[i].start>newInterval.end)      //不会重合                res.push_back(intervals[i]);            else if(flag == 0)            {                flag = 1;                Interval tmp = intervals[i];                tmp.start = min(tmp.start,newInterval.start);       //更新左端点                while(i<n && intervals[i].start<=newInterval.end)   //有重合                {                    tmp.end = max(intervals[i].end,newInterval.end);                    i++;                }                res.push_back(tmp);                i--;            }        }        if(flag == 0)            res.push_back(newInterval);        sort(res.begin(),res.end(),cmp);        //答案要有序        return res;    }};