Problem description:

Given an array of meeting time intervals consisting of start and end times [[s1,e1],[s2,e2],…] (si < ei), determine if a person could attend all meetings.

Example 1:

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Input: [[0,30],[5,10],[15,20]]
Output: false

Example 2:

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Input: [[7,10],[2,4]]
Output: true

Solution:

Use lambda function to sort, if previous meeting is longer than the latter meeting, then the person can not attend all meetings.

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/**
 * 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:
    bool canAttendMeetings(vector<Interval>& intervals) {
        sort(intervals.begin(), intervals.end(), [&](Interval a, Interval b){return a.start< b.start;});
        for(int i= 1; i< intervals.size(); i++){
            if(intervals[i-1].end > intervals[i].start)
                return false;
        }
        return true;
    }
};

time complexity: $O(nlogn)$, sorting
space complexity: $O(1)$
reference: