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

/**
 * Definition of Interval:
 * class Interval {
 * public:
 *     int start, end;
 *     Interval(int start, int end) {
 *         this->start = start;
 *         this->end = end;
 *     }
 * }
 */
class Solution {
public:
    /**
     * Insert newInterval into intervals.
     * @param intervals: Sorted interval list.
     * @param newInterval: new interval.
     * @return: A new interval list.
     */
    vector<Interval> insert(vector<Interval> &intervals, Interval newInterval) {
        // write your code here
        vector<Interval> result;
        Interval pre = newInterval;
        for (int i = 0; i < intervals.size(); i++) {
            if (pre.end < intervals[i].start) {
                result.push_back(pre);
                pre = intervals[i];
            }
            else if (pre.start > intervals[i].end) {
                result.push_back(intervals[i]);
            }
            else {
                pre.start = min(pre.start, intervals[i].start);
                pre.end = max(pre.end, intervals[i].end);
            }
        }
        result.push_back(pre);
        return result;
    }
};