Given an unsorted array return whether an increasing subsequence of length 3 exists or not in the array.

public class Solution {
    public boolean increasingTriplet(int[] nums) {
        if (nums == null || nums.length == 0) return false;

        int min = Integer.MAX_VALUE, secondMin = Integer.MAX_VALUE;
        for (int num : nums) {
            if (num <= min) {
                min = num;
            } else if (num <= secondMin) {
                secondMin = num;
            } else {
                return true;
            }
        }
        return false;
    }
}

class Solution(object):
    def increasingTriplet(self, nums):
        """
        :type nums: List[int]
        :rtype: bool
        """

        first = second = 2 ** 31 - 1
        for num in nums:
            if num <= first:
                first = num
            elif num <= second:
                second = num
            else:
                return True
        return False