14. Insert Interval FROM Leetcode

题目

Given a set of non-overlapping intervals, insert a new interval into the intervals (merge if necessary).

You may assume that the intervals were initially sorted according to their start times.

Example 1:
Given intervals [1,3],[6,9], insert and merge [2,5] in as [1,5],[6,9].

Example 2:
Given [1,2],[3,5],[6,7],[8,10],[12,16], insert and merge [4,9] in as [1,2],[3,10],[12,16].

This is because the new interval [4,9] overlaps with [3,5],[6,7],[8,10].

解题之法

/**
 * 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> insert(vector<Interval>& intervals, Interval newInterval) {
    vector<Interval> ret;
    auto it = intervals.begin();
    for(; it!=intervals.end(); ++it){
        if(newInterval.end < (*it).start) //all intervals after will not overlap with the newInterval
            break; 
        else if(newInterval.start > (*it).end) //*it will not overlap with the newInterval
            ret.push_back(*it); 
        else{ //update newInterval bacause *it overlap with the newInterval
            newInterval.start = min(newInterval.start, (*it).start);
            newInterval.end = max(newInterval.end, (*it).end);
        }   
    }
    // don't forget the rest of the intervals and the newInterval
    ret.push_back(newInterval);
    for(; it!=intervals.end(); ++it)
        ret.push_back(*it);
    return ret;
}
};