Add Py solution to LC354

Author: kate-melnykova

LC354-Russian-Doll-Envelopes.py

@@ -0,0 +1,71 @@
+"""
+You are given a 2D array of integers envelopes where
+envelopes[i] = [wi, hi] represents the width and the
+height of an envelope.
+
+One envelope can fit into another if and only if both
+the width and height of one envelope are greater than
+the other envelope's width and height.
+
+Return the maximum number of envelopes you can Russian
+doll (i.e., put one inside the other).
+
+Note: You cannot rotate an envelope.
+
+Example 1:
+Input: envelopes = [[5,4],[6,4],[6,7],[2,3]]
+Output: 3
+Explanation: The maximum number of envelopes you can
+Russian doll is 3 ([2,3] => [5,4] => [6,7]).
+
+Example 2:
+Input: envelopes = [[1,1],[1,1],[1,1]]
+Output: 1
+
+
+Constraints:
+1 <= envelopes.length <= 5000
+envelopes[i].length == 2
+1 <= wi, hi <= 104
+"""
+from typing import List
+import itertools
+import bisect
+
+
+class Solution:
+    def maxEnvelopes(self, envelopes: List[List[int]]) -> int:
+        """
+        n = len(envelopes)
+        Runtime complexity: O(n log n)
+        Space complexity: O(n)
+        """
+        widths = list(sorted(set(e[0] for e in envelopes)))
+        heights = {h: i for i, h in enumerate(sorted(set(e[1] for e in envelopes)))}
+        envelopes_dct = dict()
+        for w, h in envelopes:
+            if w not in envelopes_dct:
+                envelopes_dct[w] = list()
+            bisect.insort(envelopes_dct[w], h)
+
+        enclosed = [0] * len(heights)
+        for w in widths:
+            for h in reversed(envelopes_dct[w]):
+                i = heights[h]
+                if i > 0:
+                    enclosed[i] = enclosed[i - 1] + 1
+                else:
+                    enclosed[i] = 1
+            enclosed = list(itertools.accumulate(enclosed, max))
+        return enclosed[-1]
+
+
+if __name__ == "__main__":
+    import run_tests
+
+    correct_answers = [
+        [[[5,4],[6,4],[6,7],[2,3]], 3],
+        [[[1,1],[1,1],[1,1]], 1]
+    ]
+    print(f"Running tests for maxEnvelopes")
+    run_tests.run_tests(Solution().maxEnvelopes, correct_answers)