Time: 40 ms (22.41%), Space: 40.9 MB (23.28%) - LeetHub

0334-increasing-triplet-subsequence/0334-increasing-triplet-subsequence.py

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+class Solution:
+    def increasingTriplet(self, nums: List[int]) -> bool:
+        """
+        Complexities:
+        Time:  O(n)
+        Space: O(n)
+
+        where n = len(nums)
+        """
+
+        # Find j candidates (where nums[i] < nums[j])
+        # - j is not 0
+        # - nums[j] is not min so far
+        # --- O(n)
+        jCandidates = []
+        minSoFar = nums[0]
+        for j in range(1, len(nums)):
+            if nums[j] <= minSoFar:
+                minSoFar = nums[j]
+            else:
+                jCandidates.append(j)
+
+        # Fail fast: 0-1 jCandidates = no increasing tuplet (one j candidate will be k)
+        if len(jCandidates) <= 1:
+            return False
+
+        # Find k candidates (where nums[j] < nums[k])
+        # - do the same iteration as j but only over j candidates
+        # --- O(n)
+        minSoFar = nums[jCandidates[0]]
+        for kPrime in range(1, len(jCandidates)):
+            if nums[jCandidates[kPrime]] <= minSoFar:
+                minSoFar = nums[jCandidates[kPrime]]
+            else:
+                return True
+
+        return False