[LeetCode][Kotlin] 456. 132 Pattern

456. 132 Pattern

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.

n개의 정수 nums의 배열이 주어지면 132 패턴은 i < j < k이고 nums[i] < nums[k] < nums[j]인 세 정수 nums[i], nums[j] 및 nums[k]의 부분 시퀀스입니다. 

nums에 132 패턴이 있으면 true를 반환하고, 그렇지 않으면 false를 반환합니다.

 

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 <= 2 * 10^5
• -10^9 <= nums[i] <= 10^9

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코드

class Solution {
    fun find132pattern(nums: IntArray): Boolean {
        val stack = ArrayDeque<Pair<Int, Int>>()
        var curMin = nums[0]

        for (i in 1..nums.lastIndex) {
            while (stack.isNotEmpty() && nums[i] >= stack.last().first) {
                stack.removeLast()
            }

            if (stack.isNotEmpty() && nums[i] > stack.last().second) {
                return true
            }

            stack.add(nums[i] to curMin)
            curMin = minOf(curMin, nums[i])
        }

        return false
    }
}