Medium

Quiz

#456 132 Pattern

APPROACH

A 132 pattern in array nums is a triple of indices i < j < k where nums[i] < nums[k] < nums[j]: the leftmost value is the smallest, the middle index holds the largest, and the rightmost is in between.

Return true if any such triple exists, otherwise false.

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].
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What is the optimal approach for this problem?