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456. 132 Pattern

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Description

Given a sequence of n integers a₁, a₂, ..., a_n, a 132 pattern is a subsequence a_i, a_j, a_k such

that i < j < k and a_i < a_k < a_j. Design an algorithm that takes a list of n numbers as input and checks whether there is a 132 pattern in the list.

Note: n will be less than 15,000.

Example 1:

Input: [1, 2, 3, 4]



Output: False



Explanation: There is no 132 pattern in the sequence.

Example 2:

Input: [3, 1, 4, 2]



Output: True



Explanation: There is a 132 pattern in the sequence: [1, 4, 2].

Example 3:

Input: [-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].

Solutions

Python3

Java

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