Add another approach fot meeting rooms

java/253-Meeting-Rooms-ii.java

@@ -32,3 +32,42 @@ public int minMeetingRooms(List<Interval> intervals) {
  return count;
  }
 }
+
+// Two pointer approach
+public class Solution {
+ public int minMeetingRooms(List<Interval> intervals) {
+ if (intervals.size() == 0) {
+ return 0;
+ }
+
+ int len = intervals.size();
+ int[] startTime = new int[len];
+ int[] endTime = new int[len];
+
+ for (int i = 0; i < len; i++) {
+ startTime[i] = intervals.get(i).start;
+ endTime[i] = intervals.get(i).end;
+ }
+
+ Arrays.sort(startTime);
+ Arrays.sort(endTime);
+
+ int res = 0;
+ int count = 0;
+ int s = 0;
+ int e = 0;
+
+ while (s < len) {
+ if (startTime[s] < endTime[e]) {
+ s++;
+ count++;
+ } else {
+ e++;
+ count--;
+ }
+ res = Math.max(res, count);
+ }
+
+ return res;
+ }
+}