[Leetcode] 334. Increasing Triplet Subsequence

Problem

정수 배열 nums가 주어지면 i < j < k 및 nums[i] < nums[j] < nums[k]와 같은 세 개의 인덱스(i, j, k)가 있으면 true를 반환한다. 그러한 인덱스가 없으면 false를 반환한다.

 

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

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

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 <= 5 * 105
• -231 <= nums[i] <= 231 - 1

 

Solution

class Solution:
    def increasingTriplet(self, nums: List[int]) -> bool:
        n = len(nums)
        minval, maxval = min(nums), max(nums)
        for i in range(1, n - 1):
            if nums[i] > minval and nums[i] < maxval:
                if min(nums[:i]) < nums[i] and nums[i] < max(nums[i+1:]):
                    return True
        return False