252.Meeting-Rooms

252. Meeting Rooms

题目地址

https://leetcode.com/problems/meeting-rooms/

题目描述

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

Example 2:
Input: [[7,10],[2,4]]
Output: true
NOTE: input types have been changed on April 15, 2019. Please reset to default code definition to get new method signature.

代码

Approach #1 Brute Force

class Solution {
  public boolean canAttendMeetings(int[][] intervals) {
        for (int i = 0; i < intervals.length; i++) {
      for (int j = i + 1; j < intervals.length; j++) {
        if (overlap(intervals[i], intervals[j])) {
          return false;
        }
      }
    }
    return true;
  }

  public boolean overlap(int[] i1, int[] i2) {
      return ((i1[0] >= i2[0] && i1[0] < i2[1]) || (i2[0] >= i1[0] && i2[0] < i1[1]));
  }
}

Approach #2 Sorting

class Solution {
  public boolean canAttendMeetings(int[][] intervals) {
    Arrays.sort(intervals, new Comparator<int[]>() {
      public int compare(int[] i1, int[] i2) {
        return i1[0] - i2[0];
      }
    });

    for (int i = 0; i < interals.length - 1; i++) {
      if (intervals[i][1] > intervals[i + 1][0]) {
        return false;
      }
    }
    return true;
  }
}