Day 3 got to an end and the best problem of day 3 was by far "132 Pattern" from Leetcode, simple but amazing problem. Here is me solving the problem of the day: https://www.youtube.com/watch?v=pqCy9Z4x4qs&feature=youtu.be

Given a sequence of n integers a[1], a[2], ..., 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.

Input: [3, 1, 4, 2] Output: True (sequence 1, 4, 2) Input: [-1, 3, 2, 0] Output: True (sequence -1, 3, 2) Input: [1, 2, 3, 4] Output: False

This problem is our introduction to the Stack data structure. Amazing interview question, we are going through 3 brute force approaches until getting to the final idea in linear time.

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