Meeting Rooms

Problem

Given an array of meeting time intervals [start, end], return true iff one person can attend every meeting (no overlap).

Constraints

• 0 ≤ intervals.length ≤ 10⁴

Approach — Core Patterns

This is a Core Patterns problem. The idea: pick the data structure best matched to the constraints and solve it in one clean pass. Work through the reference code below line by line, then re-derive it yourself in the editor — that's how the pattern sticks.

Complexity: see the walkthrough below.

Solution code

Python

class Solution:
    def canAttendMeetings(self, intervals):
        intervals.sort()
        for i in range(1, len(intervals)):
            if intervals[i][0] < intervals[i - 1][1]:
                return False
        return True

Java

import java.util.*;

class Solution {
    public boolean canAttendMeetings(int[][] intervals) {
        Arrays.sort(intervals, (a, b) -> a[0] - b[0]);
        for (int i = 1; i < intervals.length; i++)
            if (intervals[i][0] < intervals[i-1][1]) return false;
        return true;
    }
}

Practice it

Reading a solution isn't the same as being able to write it under pressure. Open this problem in the in-browser editor, hide the solution, and solve it from scratch — your code runs against real test cases instantly.