LeetCode 252. Meeting Rooms

Author: raul-sauco

README.md

@@ -141,6 +141,7 @@ Solutions to LeetCode problems. The first column links to the problem in LeetCod
 | [239. Sliding Window Maximum][lc239]                                           | 🔴 Hard    | [![python](res/py.png)][lc239py]                                                    |
 | [240. Search a 2D Matrix II][lc240]                                            | 🟠 Medium  | [![python](res/py.png)][lc240py]                                                    |
 | [242. Valid Anagram][lc242]                                                    | 🟢 Easy    | [![python](res/py.png)][lc242py]                                                    |
+| [252. Meeting Rooms][lc252] [🔒][lintcode920]                                  | 🟢 Easy    | [![python](res/py.png)][lc252py]                                                    |
 | [256. Paint House][lc256] [🔒][lintcode515]                                    | 🟠 Medium  | [![python](res/py.png)][lc256py]                                                    |
 | [261. Graph Valid Tree][lc261] [🔒][lintcode178]                               | 🟠 Medium  | [![python](res/py.png)][lc261py]                                                    |
 | [268. Missing Number][lc268]                                                   | 🟢 Easy    | [![python](res/py.png)][lc268py]                                                    |
@@ -558,6 +559,9 @@ Solutions to LeetCode problems. The first column links to the problem in LeetCod
 [lc240py]: leetcode/search-a-2d-matrix-ii.py
 [lc242]: https://leetcode.com/problems/valid-anagram/
 [lc242py]: leetcode/valid-anagram.py
+[lc252]: https://leetcode.com/problems/meeting-rooms/
+[lc252py]: leetcode/meeting-rooms.py
+[lintcode920]: https://www.lintcode.com/problem/920/
 [lc256]: https://leetcode.com/problems/paint-house/
 [lintcode515]: https://www.lintcode.com/problem/515
 [lc256py]: leetcode/paint-house.py

leetcode/lists/neetcode.md

@@ -494,21 +494,22 @@ From their website:
 
 ## Intervals
 
-|     | B75 | Level     | Problem                                                | Solutions                             |
-| :-: | --- | --------- | ------------------------------------------------------ | ------------------------------------- |
-| ✅  | ⭐  | 🟠 Medium | [57. Insert Interval][lc57]                            | [![python](../../res/py.png)][lc57py] |
-| ✅  | ⭐  | 🟠 Medium | [56. Merge Intervals][lc56]                            | [![python](../../res/py.png)][lc56py] |
-|     | ⭐  | 🟠 Medium | [435. Non-overlapping Intervals][lc435]                |                                       |
-|     | ⭐  | 🟢 Easy   | [252. Meeting Rooms][lc252] [🔒][lintcode920]          |                                       |
-|     | ⭐  | 🟠 Medium | [253. Meeting Rooms II][lc253] [🔒][lintcode921]       |                                       |
-|     |     | 🔴 Hard   | [1851. Minimum Interval to Include Each Query][lc1851] |                                       |
+|     | B75 | Level     | Problem                                                | Solutions                              |
+| :-: | --- | --------- | ------------------------------------------------------ | -------------------------------------- |
+| ✅  | ⭐  | 🟠 Medium | [57. Insert Interval][lc57]                            | [![python](../../res/py.png)][lc57py]  |
+| ✅  | ⭐  | 🟠 Medium | [56. Merge Intervals][lc56]                            | [![python](../../res/py.png)][lc56py]  |
+|     | ⭐  | 🟠 Medium | [435. Non-overlapping Intervals][lc435]                |                                        |
+| ✅  | ⭐  | 🟢 Easy   | [252. Meeting Rooms][lc252] [🔒][lintcode920]          | [![python](../../res/py.png)][lc252py] |
+|     | ⭐  | 🟠 Medium | [253. Meeting Rooms II][lc253] [🔒][lintcode921]       |                                        |
+|     |     | 🔴 Hard   | [1851. Minimum Interval to Include Each Query][lc1851] |                                        |
 
 [lc57]: https://leetcode.com/problems/insert-interval/
 [lc57py]: ../insert-interval.py
 [lc56]: https://leetcode.com/problems/merge-intervals/
 [lc56py]: ../merge-intervals.py
 [lc435]: https://leetcode.com/problems/non-overlapping-intervals/
 [lc252]: https://leetcode.com/problems/meeting-rooms/
+[lc252py]: ../meeting-rooms.py
 [lintcode920]: https://www.lintcode.com/problem/920/
 [lc253]: https://leetcode.com/problems/meeting-rooms-ii/
 [lintcode921]: https://www.lintcode.com/problem/921/

leetcode/meeting-rooms.py

@@ -0,0 +1,68 @@
+# 252. Meeting Rooms
+# 🟢 Easy
+#
+# https://leetcode.com/problems/meeting-rooms/
+#
+# Tags: Array - Sorting - Interval
+
+import timeit
+from typing import List
+
+
+# Definition of Interval:
+class Interval(object):
+    def __init__(self, start, end):
+        self.start = start
+        self.end = end
+
+    def __repr__(self):
+        return f"Interval({self.start},{self.end})"
+
+
+# Sort the intervals, then iterate over them making sure that the start
+# time of all intervals is the same or later than the end time of the
+# previous interval.
+#
+# Time complexity: O(n*log(n)) - The sorting step has the highest cost.
+# Space complexity: O(n) - sort() in Python can take up to n/2 we could
+# implement our ows sorting to bring it down to O(1).
+#
+# Runtime: 162 ms, faster than 97.00% on LintCode.
+# Memory Usage: 9.08 MB, less than 97.00%
+class Sorting:
+    def canAttend(self, intervals: List[Interval]) -> bool:
+        intervals.sort(key=lambda interval: interval.start)
+        for i in range(1, len(intervals)):
+            if intervals[i].start < intervals[i - 1].end:
+                return False
+        return True
+
+
+def test():
+    executors = [Sorting]
+    tests = [
+        [[(5, 8), (9, 15)], True],
+        [[(0, 8), (8, 10), (15, 20)], True],
+        [[(0, 30), (5, 10), (15, 20)], False],
+    ]
+    for executor in executors:
+        start = timeit.default_timer()
+        for _ in range(1):
+            for col, t in enumerate(tests):
+                sol = executor()
+                result = sol.canAttend(
+                    [Interval(start, end) for start, end in t[0]]
+                )
+                exp = t[1]
+                assert result == exp, (
+                    f"\033[93m» {result} <> {exp}\033[91m for"
+                    + f" test {col} using \033[1m{executor.__name__}"
+                )
+        stop = timeit.default_timer()
+        used = str(round(stop - start, 5))
+        cols = "{0:20}{1:10}{2:10}"
+        res = cols.format(executor.__name__, used, "seconds")
+        print(f"\033[92m» {res}\033[0m")
+
+
+test()