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[LeetCode] Merge Intervals

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].

在LeetCode“Insert Interval”的基础上写的代码:

/** * 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> merge(vector<Interval> &intervals) {        int len = intervals.size();        vector<Interval> res;        for(int i=0;i<len;i++){          res = insert(res,intervals[i]);        }        return res;    }private:    vector<Interval> insert(vector<Interval> &intervals, Interval newInterval) {        vector<Interval> result;        Interval temp;        int len = intervals.size();        if(len==0){ //特殊情况,intervals是空时直接可以得到结果            result.push_back(newInterval);            return result;        }                    int startIndex,endIndex;        int i,startflag=0,endflag=0;        for(i = 0;i<len;){            if(intervals[i].start<=newInterval.start && intervals[i].end >= newInterval.end){//新区间在某个区间内                return intervals;            }else if(startflag == 0 && intervals[i].start > newInterval.end ){//新区间在所有区间外,在某个区间之前                result.push_back(newInterval);                startflag = 1;                endflag = 1;                break;            }else if(intervals[i].end < newInterval.start && i!=len-1){//新区间的起点在此区间之后                result.push_back(intervals[i]);                i++;            }else if(startflag == 0 && newInterval.start < intervals[i].start &&                 newInterval.end >=  intervals[i].start && newInterval.end <= intervals[i].end){//新区间的起点在此区间之前,终点在此区间之间                startflag = 1;                endflag = 1;                temp.start  = newInterval.start;                temp.end    = intervals[i].end;                result.push_back(temp);                i++;                break;            }else if(startflag == 0 && newInterval.start < intervals[i].start &&                newInterval.end > intervals[i].end){ //新区间的起点在此区间之前,终点超出此区间                startflag = 1;                temp.start  = newInterval.start;                            }else if(startflag == 0 && newInterval.start >= intervals[i].start &&                newInterval.start <=  intervals[i].end && newInterval.end > intervals[i].end){//新区间的起点在此区间之间,终点超出此区间                startflag = 1;                temp.start  = intervals[i].start;                            }else if(startflag == 0  && i==len-1 && intervals[i].end< newInterval.start){//新区间在最后一个区间外                result.push_back(intervals[i]);                result.push_back(newInterval);                return result;                }            if(startflag==1 && endflag==0 && i==len-1 && newInterval.end >intervals[i].end){//新区间的终点在最后一个区间之后                temp.end = newInterval.end;                endflag = 1;                i++;                result.push_back(temp);                return result;                             }else if(startflag==1 && endflag==0 && newInterval.end > intervals[i].end){//新区间的终点越过此区间                i++;                continue;            }else if(startflag==1 && endflag==0 && newInterval.end < intervals[i].start){//新区间的终点在此区间之前               endflag = 1;               temp.end = newInterval.end;               result.push_back(temp);               break;            }else if(startflag==1 && endflag==0 && newInterval.end >= intervals[i].start &&                newInterval.end <= intervals[i].end){//新区间的终点在此区间之间                endflag = 1;                temp.end = intervals[i].end;                i++;                result.push_back(temp);                break;            }        }//end for                            while(i<len){           result.push_back(intervals[i++]);        }        return result;    }//end func};