LC#252, optimal-find if a person could attend all meetings, O(NlogN) Time, O(1) Space

Author: NirmalSilwal

Leetcode/easy/MeetingRooms252.java

@@ -1,5 +1,7 @@
 package easy;
 
+import java.util.Arrays;
+
 /*
 Given an array of meeting time intervals where intervals[i] = [starti, endi], 
 determine if a person could attend all meetings.
@@ -16,7 +18,7 @@
 public class MeetingRooms252 {
 
 	// O(N^2) Time | O(1) Space
-	public static boolean canAttendMeetings(int[][] intervals) {
+	public static boolean canAttendMeetings1(int[][] intervals) {
 
 		for (int id = 0; id < intervals.length; id++) {
 
@@ -56,14 +58,29 @@ private static boolean isOverlapping(int start1, int end1, int start2, int end2)
 		return false;
 	}
 
+	// O(NlogN) Time | O(1) Space
+	public static boolean canAttendMeetings(int[][] intervals) {
+
+		Arrays.sort(intervals, (a, b) -> Integer.compare(a[0], b[0]));
+
+		for (int id = 0; id < intervals.length - 1; id++) {
+			if (intervals[id][1] > intervals[id + 1][0]) {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
 	public static void main(String[] args) {
 
-		// test cases
+		/* test cases */
 		// [[8,11],[17,20],[17,20]]
 		// [[13,15],[1,13]]
 		// { 7, 10 }, { 2, 4 }
 
 		int[][] intervals = { { 0, 30 }, { 5, 10 }, { 15, 20 } }; // false
+		System.out.println(canAttendMeetings1(intervals));
 		System.out.println(canAttendMeetings(intervals));
 	}
 }