[LeetCode] Merge Intervals 排序sort

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].

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Array Sort

1. 按start 排序
2. 初始化变量curstart,curend,记录当前窗的位置。
3. 与下个窗比较，如果其start < curend，更新 curend。
4. 否则加入ret，并跟新curstart,curend
5. 遍历结束，加入最后的窗。

 1 #include <iostream>
 2 #include <vector>
 3 #include <algorithm>
 4 using namespace std;
 5
 6 /**
 7  * Definition for an interval.
 8  */
 9  struct Interval {
10     int start;
11     int end;
12     Interval() : start(0), end(0) {}
13     Interval(int s, int e) : start(s), end(e) {}
14 };
15
16 class Solution {
17 public:
18     vector<Interval> merge(vector<Interval> &intervals) {
19         sort(intervals.begin(),intervals.end(),20              [] (Interval i1,Interval i2)21              {return i1.start<i2.start; });
22
23 ///        sort(intervals.begin(),intervals.end(),help_fun);
24
25 /**        struct my_cmp{
26             bool operator ()(Interval i1,Interval i2){
27                 return i1.start<i2.start;
28             }
29         }my_cmp1;
30         sort(intervals.begin(),intervals.end(),my_cmp());
31         sort(intervals.begin(),intervals.end(),my_cmp1);
32 */
33
34 //        for(int i=0;i<intervals.size();i++){
35 //            cout<<intervals[i].start<<" "<<intervals[i].end<<endl;
36 //        }
37         vector<Interval> ret;
38         if(intervals.size()<1)  return ret;
39         int curStart=intervals[0].start,curEnd=intervals[0].end;
40         for(int i=1;i<intervals.size();i++){
41             if(curEnd>=intervals[i].start){
42                 if(intervals[i].end>curEnd) curEnd=intervals[i].end;
43                 continue;
44             }
45             ret.push_back(Interval(curStart,curEnd));
46             curStart = intervals[i].start;
47             curEnd = intervals[i].end;
48         }
49         ret.push_back(Interval(curStart,curEnd));
50         return ret;
51     }
52
53     static bool help_fun(Interval i1,Interval i2)
54     {
55         return i1.start<i2.start;
56     }
57 };
58
59 int main()
60 {
61     vector<Interval> intervals={Interval(8,10),62                                 Interval(2,6),63                                 Interval(1,3),64                                 Interval(15,18)};
65     Solution sol;
66     vector<Interval> ret = sol.merge(intervals);
67
68     for(int i=0;i<ret.size();i++){
69         cout<<ret[i].start<<" "<<ret[i].end<<endl;
70     }
71     return 0;
72 }