leetcode334. Increasing Triplet Subsequence

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

Formally the function should:

Return true if there exists i, j, k 
such that arr[i] < arr[j] < arr[k] given 0 ≤ i < j < k ≤ n-1 else return false.
Note: Your algorithm should run in O(n) time complexity and O(1) space complexity.

Example 1:

Input: [1,2,3,4,5]
Output: true
Example 2:

Input: [5,4,3,2,1]
Output: false

    public boolean increasingTriplet(int[] nums) {
        if(nums == null || nums.length < 3) return false;
        
        boolean[] hasLeftMin = new boolean[nums.length];
        boolean[] hasRightMax = new boolean[nums.length];
        
        int left = 0;
        int right = nums.length - 1;
        for(int i = 1 ; i<nums.length-1 ; i++) {
            if(nums[i] > nums[left]) {
                hasLeftMin[i] = true;
            } else {
                left = i;
            }
            if(nums[nums.length - i - 1] < nums[right]) {
                hasRightMax[nums.length - i - 1] = true;
            } else {
                right = nums.length - i - 1;
            }
        }
        
        for(int i = 1 ; i < nums.length - 1 ; i++) {
            if(hasLeftMin[i] && hasRightMax[i]) return true;
        }
        return false;
    }

    public boolean increasingTriplet(int[] nums) {
        int small = Integer.MAX_VALUE, big = Integer.MAX_VALUE;
        for(int n : nums) {
            if(n <= small) {
                small = n;
            } else if (n<=big) {
                big = n;
            } else {
                return true;
            }
        }
        return false;
    }