【leetcode】Merge Intervals

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].

 

 

先排序，然后循环合并

 

 /**
  * 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) {
         vector<Interval> result;
         if(intervals.empty()) return result;

         sort(intervals.begin(),intervals.end(),cmp);

         int start=intervals[].start;
         int end=intervals[].end;

         for(int i=;i<intervals.size();i++)
         {
             if(intervals[i].start<=end)
             {
                 //注意[1,4],[2,3]的情况
                 end=end<intervals[i].end?intervals[i].end:end;
             }
             else
             {
                 result.push_back(Interval(start,end));
                 start=intervals[i].start;
                 end=intervals[i].end;
             }
         }

         result.push_back(Interval(start,end));
         return result;
     }

     static int cmp(const Interval &a,const Interval &b)
     {
         if(a.start<b.start) return ;
         else if(a.start>b.start) return ;
         else return a.end<b.end;
     }
 };