💡 Problem Formulation: Consider a given mapping where digits are associated with certain characters, similar to the way digits are linked to letters on a telephone keypad. The problem involves finding all possible strings that can be formed from the characters corresponding to a given sequence of digits. For instance, if ‘2’ maps to ‘abc’ … Read more
💡 Problem Formulation: Given a postorder traversal of a binary search tree (BST), the task is to reconstruct the original BST. The postorder traversal is a sequence of values visited as per postorder traversal of the BST. For instance, if the input postorder array is [1, 3, 2, 5, 7, 6, 4], the desired output … Read more
💡 Problem Formulation: A primorial prime is a prime number that is one less or one more than a primorial. The primorial of a number is the product of the first n primes. Our objective is to determine whether a given number is a primorial prime. If we take the input 30, for example, the … Read more
💡 Problem Formulation: What is an Achilles number? An Achilles number is a number that is powerful, meaning all of its prime factors are squared, but it is not a perfect power (i.e., it cannot be expressed as m^n for any integers m > 1 and n > 1). In this article, we explore five … Read more
💡 Problem Formulation: The task is to identify all unique substrings within a provided string that read the same backwards as forwards, known as palindromes. For example, given the input string “aabbbaa”, the desired output should be a set of distinct palindromes such as {“a”, “aa”, “b”, “bb”, “bbb”, “abbba”, “aabbbaa”}. Method 1: Brute Force … Read more
💡 Problem Formulation: In Python, checking if a number is a “Trojan number”—a number that remains the same when its digits are squared and concatenated—requires specific checks and computations. The goal is to input a number and determine whether it is a Trojan number. For instance, the input 248 should return True since squaring and … Read more
💡 Problem Formulation: This article addresses the challenge of identifying strings where each character is lexicographically greater than its immediate follower. For instance, given the input ‘cbad’, the desired output is ‘true’ since ‘c’ > ‘b’, ‘b’ > ‘a’, and ‘a’ > ‘d’. Conversely, for ‘abcd’, the output should be ‘false’ as the sequence does … Read more
💡 Problem Formulation: We are faced with a scenario where we must determine the legality of a king’s move on a chessboard that has been altered by the presence of ‘n’ knights. With Python, we wish to assess if there exists at least one valid move for the king. An example input would be the … Read more
💡 Problem Formulation: We aim to find a string that is lexicographically between two given strings. This means the string should appear after the first string and before the second string when sorted alphabetically. For instance, given strings “apple” and “banana”, a desired output might be “apricot” as it fits lexicographically between them. Method 1: … Read more
💡 Problem Formulation: Given a list of numbers, the goal is to find a sorted subsequence of size 3, where the numbers are in ascending order, without sorting the entire list. This challenge requires a solution that runs in O(n) time complexity. As an example, for the input list [4, 3, 2, 5, 1], a … Read more
💡 Problem Formulation: The challenge is to determine a positive integer m that, given a positive integer n, maximizes the Greatest Common Divisor (gcd) of n and m. For instance, if the input n is 10, a desired output for m would be 5, yielding the maximum gcd of 5. Method 1: Brute Force Search … Read more
💡 Problem Formulation: We aim to identify a single number that, when XORed with every element in an array of integers, results in the minimum possible sum of the outcomes. For instance, given the input array [1, 2, 3], a solution would return a number x such that (1 XOR x) + (2 XOR x) … Read more