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【LeetCode】Insert Interval
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].
由于insert和erase代价太大，需要移动后面所有元素。
所有空间换时间，返回新的数组ret，而不采用inplace做法。
主要以下三种情况：
1、newInterval在当前interval之前，则把newInterval装入ret，然后装入所有后续interval。返回ret。
2、newInterval与当前interval有交集，
（1）newInterval的end不大于当前interval的end，说明与后续元素没有交集，则合并为当前interval，然后将当前interval及后续interval装入ret。返回ret。
（2）newInterval的end大于当前interval的end
（2.1）newInterval的start大于当前interval的end，则将当前interval装入ret，然后处理下一个interval。
（2.2）newInterval的start不大于当前interval的end，则合并为新的newInterval，然后处理下一个interval。
3、处理完最后一个interval若仍未返回ret，说明newInterval为最后一个interval，装入ret。返回ret。
/** * 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; if(intervals.empty()) {//newInterval is ret ret.push_back(newInterval); return ret; } vector<Interval>::iterator it= intervals.begin(); while(it != intervals.end()) { if(newInterval.end < (*it).start) {//newInterval is strictly before (*it) ret.push_back(newInterval); while(it != intervals.end()) { ret.push_back(*it); it ++; } return ret; //end } else if(newInterval.end <= (*it).end) {//remains unchanged or (*it).start=newIntervals.start (*it).start = min((*it).start, newInterval.start); while(it != intervals.end()) { ret.push_back(*it); it ++; } return ret; //end } else {//newInterval.end > (*it).end if(newInterval.start <= (*it).end) {//overlap, change (*it) into newInterval if(newInterval.start > (*it).start) //update start newInterval.start = (*it).start; } else //newInterval is strictly after (*it) ret.push_back(*it); it ++; } } ret.push_back(newInterval); return ret; }};
【LeetCode】Insert Interval