LeetCode 252. Meeting Rooms

原题链接在这里：https://leetcode.com/problems/meeting-rooms/

题目：

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.

For example,
Given [[0, 30],[5, 10],[15, 20]],
return false.

题解：

对array进行排序，从i = 1开始判断start是否在前一个end之前, 若是就return false. 完成loop返回true.

Time Complexity: O(nlogn). Space: O(1).

AC Java:

/**
 * Definition for an interval.
 * public class Interval {
 *     int start;
 *     int end;
 *     Interval() { start = 0; end = 0; }
 *     Interval(int s, int e) { start = s; end = e; }
 * }
 */
public class Solution {
    public boolean canAttendMeetings(Interval[] intervals) {
        if(intervals == null || intervals.length == 0){
            return true;
        }
        Arrays.sort(intervals, new Comparator<Interval>(){
            public int compare(Interval i1, Interval i2){
                if(i1.start == i2.start){
                    return i1.end - i2.end;
                }
                return i1.start - i2.start;
            }
        });
        
        for(int i = 1; i<intervals.length; i++){
            if(intervals[i].start < intervals[i-1].end){
                return false;
            }
        }
        return true;
    }
}

 跟上Meeting Rooms II, Maximum Number of Events That Can Be Attended.