[leetcode] 57. Insert Interval 解题报告

题目链接：https://leetcode.com/problems/insert-interval/

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].

思路：找出左右边界即可，然后将新的区间都copy到新容器中，时间复杂度为O(n)．

代码如下：

/**
 * 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> result;
        int left = newInterval.start, right = newInterval.end;
        for(auto intvl: intervals)
        {
            if(intvl.end < newInterval.start)
                result.push_back(intvl);
            if(intvl.end >= newInterval.start)
                left = min(left, intvl.start);
            if(intvl.start <= newInterval.end)
                right = max(right, intvl.end);
        }
        Interval tem(left, right);
        result.push_back(tem);
        for(auto intvl: intervals)
            if(intvl.start > newInterval.end)
                result.push_back(intvl);
        return result;
    }
};

参考：https://leetcode.com/discuss/42018/7-lines-3-easy-solutions