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Articles on Trending Technologies
Technical articles with clear explanations and examples
Find the longest substring with k unique characters in a given string in Python
Finding the longest substring with exactly k unique characters is a classic sliding window problem. We use two pointers to maintain a window and expand or shrink it based on the number of unique characters. Problem Understanding Given a string and a number k, we need to find the longest substring that contains exactly k unique characters. For example, in "ppqprqtqtqt" with k=3, the answer is "rqtqtqt" which has length 7 and contains exactly 3 unique characters: 'r', 'q', and 't'. Algorithm Steps The solution uses a sliding window approach ? First, check if ...
Read MoreFind the longest subsequence of an array having LCM at most K in Python
Given an array of numbers and a positive integer K, we need to find the longest subsequence where the Least Common Multiple (LCM) is at most K. The function returns the LCM value, length of the subsequence, and indices of elements in the optimal subsequence. Problem Understanding For example, if we have array A = [3, 4, 5, 6] and K = 20, we need to find which combination of elements gives us the longest subsequence with LCM ≤ 20. The LCM of [3, 4, 6] is 12, which is ≤ 20, and this gives us the longest ...
Read MoreFind the longest sub-string which is prefix, suffix and also present inside the string in Python
Given a string, we need to find the longest substring that appears as a prefix, suffix, and also somewhere inside the string. This problem uses the concept of the Longest Prefix Suffix (LPS) array from the KMP algorithm. For example, in the string "languagepythonlanguageinterestinglanguage", the substring "language" appears at the beginning, end, and middle of the string. Algorithm Overview We use a two-step approach: Build the LPS (Longest Prefix Suffix) array using the KMP preprocessing algorithm Find the longest substring that satisfies our conditions using the LPS array Building the LPS Array ...
Read MoreFind the lexicographically smallest string which satisfies the given condition in Python
Given an array A of n numbers where A[i] indicates the number of distinct characters in the prefix of length (i + 1) of a string s, we need to find the lexicographically smallest string that satisfies the given prefix array. All characters will be lowercase English alphabets [a-z]. If no such string exists, return -1. For example, if A = [1, 1, 2, 3, 4], the output will be "aabcd" because prefix[0] has 1 distinct character, prefix[1] has 1 distinct character, prefix[2] has 2 distinct characters, prefix[3] has 3 distinct characters, and prefix[4] has 4 distinct characters, and ...
Read MoreFind the lexicographically largest palindromic Subsequence of a String in Python
Sometimes we need to find the lexicographically largest palindromic subsequence of a string. A palindromic subsequence reads the same forwards and backwards, and the lexicographically largest one uses the highest character in the string. The key insight is that the lexicographically largest palindromic subsequence consists of all occurrences of the maximum character in the string, since identical characters always form a palindrome. So, if the input is like "tutorialspointtutorial", then the output will be "uu". Algorithm Steps To solve this, we will follow these steps − Initialize ans as empty ...
Read MoreFind the largest rectangle of 1's with swapping of columns allowed in Python
Given a binary matrix, we need to find the largest rectangle of all 1's that can be formed by swapping any columns. This problem combines the classic "largest rectangle in histogram" algorithm with column optimization. Problem Understanding Consider this matrix ? 1 0 0 1 0 1 0 0 1 1 1 1 0 1 0 By swapping columns 1 and 3, we get ? 0 0 1 1 0 0 0 1 1 1 1 0 1 1 0 ...
Read MoreFind the largest Perfect Subtree in a given Binary Tree in Python
A Perfect Binary Tree is a binary tree where all internal nodes have exactly two children and all leaves are at the same level. This article explains how to find the size of the largest perfect subtree within a given binary tree using Python. 2 3 4 5 6 7 ...
Read MoreFind the index which is the last to be reduced to zero after performing a given operation in Python
Given an array and a value K, we need to find which index will be the last element to reach zero after repeatedly performing a subtraction operation. In each operation, we subtract K from each non-zero element, and if any element becomes less than K, it's set to zero. Problem Understanding The operation works as follows ? Start from A[0] to A[N − 1], update each element as A[i] = A[i] − K If A[i] < K, then set A[i] = 0 Once an element becomes 0, no further operations are performed on it Repeat until ...
Read MoreFind the element before which all the elements are smaller than it, and after which all are greater in Python
In array processing, we sometimes need to find a special element that acts as a pivot point — an element where all elements to its left are smaller, and all elements to its right are greater. This problem requires finding such an element and returning its index, or -1 if no such element exists. Problem Understanding Given an array, we need to find an element where: All elements before it are smaller than the element All elements after it are greater than the element For the array [6, 2, 5, 4, 7, 9, 11, 8, ...
Read MoreFind the distance covered to collect items at equal distances in Python
In this problem, we need to calculate the total distance covered by a participant who collects stones placed at equal intervals and returns each stone to a starting bucket. The setup is as follows: A bucket is placed at the starting point The first stone is 6 units away from the bucket Each subsequent stone is 4 units apart from the previous one The participant must collect stones one by one, returning to the bucket after each collection Bucket ...
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