Solution.py

"""

Given an integer array nums, return true if there exists a triple of indices (i, j, k) such that i < j < k and nums[i] < nums[j] < nums[k]. If no such indices exists, return false.
 
Example 1:

Input: nums = [1,2,3,4,5]
Output: true
Explanation: Any triplet where i < j < k is valid.

Example 2:

Input: nums = [5,4,3,2,1]
Output: false
Explanation: No triplet exists.

Example 3:

Input: nums = [2,1,5,0,4,6]
Output: true
Explanation: The triplet (3, 4, 5) is valid because nums[3] == 0 < nums[4] == 4 < nums[5] == 6.

 
Constraints:

1 <= nums.length <= 105
-231 <= nums[i] <= 231 - 1

 
Follow up: Could you implement a solution that runs in O(n) time complexity and O(1) space complexity?
"""


class Solution:
    def increasingTriplet(self, nums: List[int]) -> bool:
        small, big = None, None
        for n in nums:
            if small is None or n <= small:
                small = n
            elif big is None or n <= big:
                big = n
            else:
                return True
        return False