💡 Problem Formulation: A palindromic subsequence is a sequence of characters that reads the same backward as forward. The challenge in this article is to determine the length of the longest palindromic subsequence from a given string input. For example, if the input is “BBABCBCAB”, the longest palindromic subsequence is “BABCBAB” or “BBCABB”, and its … Read more
💡 Problem Formulation: A “good” leaf node pair is defined as a pair of leaf nodes with a distance of at most d edges between them. The objective is to write a Python program that takes as input a binary tree and an integer d, and returns the number of good leaf node pairs. For … Read more
💡 Problem Formulation: The task is to find the total number of subsequences of an array whose sum equals a specific target value. Given an input array [3,1,2,1] and a target sum 3, an algorithm should output the number of subsequences that sum up to the target, which here is 3: [3], [1,2], and [2,1]. … Read more
💡 Problem Formulation: You are given a binary grid (a 2D array), where rows can be swapped with one another. The objective is to find the minimum number of row swaps required to arrange this grid so that all 1’s move to the leading side of the rows, with rows having more 1’s being higher … Read more
💡 Problem Formulation: The task is determining if a given string can be transformed into a target string by changing its characters, with the restriction that you can only make a maximum of ‘k’ character changes. For example, given the initial string “abc” and the target string “def”, we wish to know if it’s possible … Read more
💡 Problem Formulation: In binary sequences, finding the value of a specific bit at position k within the nth binary number is a common task. Given an integer n, consider this as a binary string after converting to binary format. The challenge is to determine the value of the bit at the kth position (from … Read more
💡 Problem Formulation: Given an array of integers and a target sum, the goal is to find the maximum number of non-overlapping subarrays that add up to the target. For example, if the input is [1, 1, 1, 1, 1] and the target is 2, the output would be 2 because there are two non-overlapping … Read more
💡 Problem Formulation: We are addressing the challenge of calculating the minimum number of operations required to make all elements in an array equal. This commonly involves tasks such as incrementing or decrementing array elements, with operations constrained to specific rules. For instance, given an input array [1, 2, 3], the minimum number of operations … Read more
💡 Problem Formulation: We aim to solve a common problem in graph theory: finding the minimum set of starting points (vertices) that allow you to reach all other nodes in a directed graph. In terms of input, imagine a graph represented by a list of edges or an adjacency list. The desired output is a … Read more
💡 Problem Formulation: In tree data structures, subtrees often represent hierarchical subsets of data. A common query might involve counting the nodes within a subtree that share a common label. For example, given a tree where each node is labelled with a letter, one might be tasked with finding the number of ‘A’-labelled nodes within … Read more
💡 Problem Formulation: In the context of array processing, a common task involves identifying subarrays whose elements sum to an odd number. Given an input array like [1, 2, 3, 4], we aim to find the count of all possible contiguous subarrays where the sum is odd. For this input, the desired output is 4, … Read more
💡 Problem Formulation: Given a string, the task is to compute the number of ‘good’ ways it can be split into two non-empty substrings, such that the number of distinct characters in both substrings is the same. For example, given the input “ababa”, a good split would result in strings “aba” and “ba” both containing … Read more