0334-increasing-triplet-subsequence.py

class Solution:
    def increasingTriplet(self, nums: List[int]) -> bool:
        first = float('inf')  # Initialize first to positive infinity
        second = float('inf')  # Initialize second to positive infinity
        
        for num in nums:
            if num <= first:
                first = num  # Update first if num is smaller or equal
            elif num <= second:
                second = num  # Update second if num is smaller or equal
            else:
                return True  # We found a triplet: first < second < num
        
        return False  # No triplet exists