In this problem, we will count the number of binary strings of size N, containing at most 2 adjacent distinct pair of characters. It means the string should contain, at most, 2 '01' 0r '10' pairs. The first approach is that generate all binary strings, and if any binary string contains less than or equal to 2 distinct pairs of characters, include its count in the result. For the optimal solution, we can count a number of binary strings containing 0, 1, and 2 adjacent different pairs and sum them. Problem statement - We have given a positive ... Read More

In this problem, we need to count substrings containing a minimum 1 occurrence of all K characters. Here, we will use two different approaches to solve the problem. The first approach takes all substrings of the given string, checks whether the substring contains all K characters, and counts such substrings containing all K characters. The second approach uses the sliding window technique to solve the problem. Problem statement - We have given a string alpha containing N characters. Also, we have given K, representing the string containing multiple occurrences of only the first K alphabetical characters. We ... Read More

In this problem, we will count the number of strings containing query string as a prefix for each query string. We can traverse the list of query strings, and for each query, we can find a number of strings containing it as a prefix. Also, we can use the trie data structure to solve the problem. Problem statement – We have given an strs[] and queStr[] string array containing N and Q strings, respectively. We need to count the number of strings from the Strs[] array containing the queStr[i] string as a prefix for each string of ... Read More

In this problem, we will check whether it is possible to convert string S to T by incrementing the characters of S only once according to the given condition. Here, we can increment any characters by 'I' only once. So, If we need to increment any other character by 'I' times, the value of K should be greater than 26 + I. Problem statement – We have given a string S, T, and positive integer K. We need to convert the string S to T by following the rules below. We can take ... Read More

In this problem, we will validate the UPI id using the regular expression. The UPI is the unified payment interface that is given to each customer, and other people can use it to transfer money to you. The UPI id contains alphanumeric characters. The UPI id should always contain a ‘@’ character. The UPI id should not have white spaces. The UPI id may have a dot(.) or hyphen(-). Problem statement − We have given an upi id in the string format. We need to validate the UPI id using the regular expression. Sample Examples Input: upi ... Read More

In this problem, we will learn to find the count of minimum deletion required so that when we take the XOR of any two adjacent elements, we should either get 0 or 1. We will use the properties of the XOR operations to solve the problem. For example, when we take XOR of the same numbers, we always get 0; when we take XOR of the consecutive even and odd number, we get 1. Problem Statement We have given a num_str string containing the numeric digits. We need to count the minimum deletions required so that the XOR ... Read More

In this problem, we will find the maximum distance from the initial to the final character in the cyclic string. The basic approach to solve the problem is to find the next closest final character for every initial character and update the maximum distance if required. Another approach traverses the string in reverse order and keeps track the index of the last final character. When we get an initial character, we measure the distance and update the maximum distance if required. Problem statement − We have given an str string containing the 3 characters, and the length equals N. Also, ... Read More

In this problem, we will maximize the value of the binary string by performing K XOR operations of substrings of the given binary string. To maximize any binary string, we should maximize the substring starting from the leftmost zero. For example, to maximize the ‘11001’ string, we need to choose another substring in such a way that we can maximize the ‘001’ substring. Problem Statement We have given a binary string named bin_str containing N characters. We have to maximize the value of the binary string in K operations by taking the XOR operation of any two substrings. It ... Read More

In this problem, we need to maximize the ‘10’ subsequences in the given binary string by replacing the 0 or 1 ‘0’ character with ‘1’. We can replace each ‘0’ with ‘1’ one after another and find a maximum number of ‘10’ subsequences in the updated string. Problem statement − We have given a binary string named str1 containing only 0 and 1 characters. We can replace at most one ‘0’ with ‘1’ and need to find the maximum number of ‘10’ subsequences in the given string. Sample Examples Input  str1 = "10110" Output  4 Explanation The ‘10110’ ... Read More

In this problem, we will find the longest substring of A to convert it to a substring of B starting from the same index in less than T cost. We will use the binary search algorithm to find the maximum length of the substring which follows the given condition. However, the naïve approach to solving the problem is to find all substrings following the conditions in the problem statement and take the substring with maximum length. Problem statement − We have given a string A and B of length N. Also, we have given a total cost, ‘T’. The ... Read More