''' Given an array of n integers nums, a 132 pattern is a subsequence of three integers nums[i], nums[j] and nums[k] such that i < j < k and nums[i] < nums[k] < nums[j]. Return true if there is a 132 pattern in nums, otherwise, return false. Follow up: The O(n^2) is trivial, could you come up with the O(n logn) or the O(n) solution? Example 1: Input: nums = [1,2,3,4] Output: false Explanation: There is no 132 pattern in the sequence. Example 2: Input: nums = [3,1,4,2] Output: true Explanation: There is a 132 pattern in the sequence: [1, 4, 2]. Example 3: Input: nums = [-1,3,2,0] Output: true Explanation: There are three 132 patterns in the sequence: [-1, 3, 2], [-1, 3, 0] and [-1, 2, 0]. Constraints: n == nums.length 1 <= n <= 104 -109 <= nums[i] <= 109 ''' class Solution: def find132pattern(self, nums: List[int]) -> bool: if len(set(nums)) < 3: return False min_nums = [nums[0]] for i in range(1, len(nums)): min_nums.append(min(nums[i], min_nums[-1])) stack = [] i = len(nums) - 1 for i in range(len(nums)-1, -1, -1): if( nums[i] > min_nums[i] ): while( stack and stack[-1] <= min_nums[i] ): stack.pop() if(stack and min_nums[i] < stack[-1] < nums[i] ): return True stack.append(nums[i]) return False