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Useful Python Libraries & Modules

Bisect Reference Incredible module for inserting and searching an array for values using a binary search Useful methods include: bisect.bisect(arr, val) - searches for the value in the array and returns an insertion point coming after any existing entries of the value bisect.bisect_left - searches for the value of the array and returns insertion point to the left of it bisect.bisect_right - same as bisect_left but for insertions to the right bisect.

    Saturday, July 27, 2024 | 1 minute Read
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    673. Number of Longest Increasing Subsequence

    Today we are finding the number of longest increasing subsequences in an integer array. Approach Since this involves finding the maximum length of something, we can make a good guess that it is a DP problem. Moreover, it does not look like we can use a two pointer greedy approach since there are multiple sequences to be found and they can be spaced out all over the array. Instead, we need to look at the problem deeper to see if there is some kind of recurrence to be exploited.

      Wednesday, July 3, 2024 | 1 minute Read
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      300. Longest Increasing Subsequence

      Here we solve 300. Longest Increasing Subsequence. It asks us for the length of the longest strictly increasing subsequence in an array. So, for the array [3, 2, 6, 2, 9, 2, 7, 1, 4, 2, 15, 16, 14, 18, 1], the answer would be 6, one of such arrays being [2, 6, 7, 15, 16, 18]. Solution We solve this problem by iteratively building a subsequence from left to right, obeying the following rules:

        Wednesday, June 19, 2024 | 2 minutes Read
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        1143. Longest Common Subsequence

        To kickstart my blog on solving leetcode problems which I deem to be worthy of a writeup (most of them since I usually end up forgetting my approach), let’s look at this classic question. The question asks, given two strings $s$ and $t$, what is the longest subsequence between them? For our example, let’s use s="abcdef" and b="bcdgf". The longest common subsequence should then be bcdf. I liken this problem to a Hydra, since it is very easy to get confused by it again even after you solve it.

          Wednesday, June 12, 2024 | 2 minutes Read