add meeting rooms solution

Author: Tessa1217

meeting-rooms/Tessa1217.java

@@ -1,2 +1,42 @@
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Definition of Interval:
+ * public class Interval {
+ *     int start, end;
+ *     Interval(int start, int end) {
+ *         this.start = start;
+ *         this.end = end;
+ *     }
+ * }
+ */
+
 public class Solution {
+    /**
+     * @param intervals: an array of meeting time intervals
+     * @return: if a person could attend all meetings
+     */
+
+    // 시간복잡도: O(n log n) - 정렬, 공간복잡도: O(1)
+    public boolean canAttendMeetings(List<Interval> intervals) {
+        // Write your code here
+
+        if (intervals == null || intervals.isEmpty()) return true;
+
+        Collections.sort(intervals, (i1, i2) -> i1.start - i2.start);
+
+        Interval previous = intervals.get(0);
+
+        for (int i = 1; i < intervals.size(); i++) {
+            Interval current = intervals.get(i);
+            if (previous.end > current.start) {
+                return false;
+            }
+            previous = current;
+        }
+
+        return true;
+    }
 }
+