Insert Intervals

Given a non-overlapping interval list which is sorted by start point.

Insert a new interval into it, make sure the list is still in order and non-overlapping (merge intervals if necessary).

Example

Insert [2, 5] into [[1,2], [5,9]], we get [[1,9]].

Insert [3, 4] into [[1,2], [5,9]], we get [[1,2], [3,4], [5,9]].

Analyse: There are three possibilities for the newInterval and currentInterval: newInterval.end < currentInterval.start, newInterval.start > currentInterval.end, and newInterval and currentInterval intersects.

Runtime: 24ms

 1 /**
 2  * Definition of Interval:
 3  * class Interval {
 4  * public:
 5  *     int start, end;
 6  *     Interval(int start, int end) {
 7  *         this->start = start;
 8  *         this->end = end;
 9  *     }
10  * }
11  */
12 class Solution {
13 public:
14     /**
15      * Insert newInterval into intervals.
16      * @param intervals: Sorted interval list.
17      * @param newInterval: new interval.
18      * @return: A new interval list.
19      */
20     vector<Interval> insert(vector<Interval> &intervals, Interval newInterval) {
21         // write your code here
22         vector<Interval> result;
23         Interval pre = newInterval;
24         for (int i = 0; i < intervals.size(); i++) {
25             if (pre.end < intervals[i].start) {
26                 result.push_back(pre);
27                 pre = intervals[i];
28             }
29             else if (pre.start > intervals[i].end) {
30                 result.push_back(intervals[i]);
31             }
32             else {
33                 pre.start = min(pre.start, intervals[i].start);
34                 pre.end = max(pre.end, intervals[i].end);
35             }
36         }
37         result.push_back(pre);
38         return result;
39     }
40 };