LeetCode: Merge Intervals [055]

【题目】

Given an array of non-negative integers, you are initially positioned at the first index of the array.

Given a collection of intervals, merge all overlapping intervals.

For example,
Given [1,3],[2,6],[8,10],[15,18],
return [1,6],[8,10],[15,18].

【题意】

给定若干区间，把存在重叠的区间合并

【思路】

       

1. 先对区间按开始值一级升序排列，然后按照结束值二级升序排列
2. 对排序后的区间依次合并即可

【代码】

/** * Definition for an interval. * struct Interval { *     int start; *     int end; *     Interval() : start(0), end(0) {} *     Interval(int s, int e) : start(s), end(e) {} * }; */  bool compare(const Interval&o1, const Interval&o2){     if(o1.start<o2.start)return true;     else if(o1.start==o2.start){         return o1.end<o2.end;     }     return false; } class Solution {public:    vector<Interval> merge(vector<Interval> &intervals) {        vector<Interval> result;        int size=intervals.size();        if(size==0)return result;        //排序        sort(intervals.begin(), intervals.end(),compare);        //合并        Interval curInterval(intervals[0].start, intervals[0].end);        for(int i=1; i<size; i++){            if(curInterval.end<intervals[i].start){                result.push_back(curInterval);                curInterval=Interval(intervals[i].start, intervals[i].end);            }            else{                if(intervals[i].end>curInterval.end)curInterval.end=intervals[i].end;            }        }        //别忘了最后一个区间        result.push_back(curInterval);        return result;    }};