solve Teemo Attacking

Author: saubhik

problems/teemo_attacking.py

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+from typing import List
+
+
+class Solution:
+    # timeSeries = [1, 3, 8, 19], duration = 5
+    def findPoisonedDuration(self, timeSeries: List[int], duration: int) -> int:
+        ans, last = 0, float("-inf")
+        for t in timeSeries:
+            ans += duration
+            if (t - last) < duration:
+                ans -= duration - (t - last)
+            last = t
+        return ans
+
+
+class OfficialSolution:
+    def findPoisonedDuration(self, timeSeries: List[int], duration: int) -> int:
+        """
+        The problem is an example of merge interval questions which are now quite
+        popular in Google.
+        Typically such problems could be solved in linear time in the case of sorted
+        input, and in O(nlgn) time otherwise.
+        Here one deals with a sorted input, and the problem could be solved in one pass
+        with a constant space. The idea is straightforward: consider only the interval
+        between two attacks. Ashe spends in a poisoned condition the whole time interval
+        if this interval is shorter than the poisoning time duration, and duration
+        otherwise.
+
+        == Algorithm ==
+        - Initiate total time in poisoned condition, total = 0.
+        - Iterate over timeSeries list. At each step add to the total time the minimum
+            between interval length and the poisoning time duration.
+        - Return total + duration to take the last attack into account.
+
+        == Complexity Analysis ==
+        - Time Complexity: O(n) where n is the length of the input list, since we
+            iterate the entire list.
+        - Space Complexity: O(1), it's a constant space solution.
+        """
+        n = len(timeSeries)
+        if n == 0:
+            return 0
+
+        total = 0
+        for i in range(n - 1):
+            total += min(timeSeries[i + 1] - timeSeries[i], duration)
+        return total + duration

tests/test_teemo_attacking.py

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+import unittest
+
+from teemo_attacking import Solution, OfficialSolution
+
+
+class TestTeemoAttacking(unittest.TestCase):
+    def test_example_1(self):
+        assert Solution().findPoisonedDuration(timeSeries=[1, 4], duration=2) == 4
+        assert (
+            OfficialSolution().findPoisonedDuration(timeSeries=[1, 4], duration=2) == 4
+        )
+
+    def test_example_2(self):
+        assert Solution().findPoisonedDuration(timeSeries=[1, 2], duration=2) == 3
+        assert (
+            OfficialSolution().findPoisonedDuration(timeSeries=[1, 2], duration=2) == 3
+        )