Suppose we have strings S and T. We have to count number of distinct sequences of S which is equal to T.We know that a subsequence of a string is a new string which is formed from the original string by removing some (can be none) of the characters without disturbing the relative positions of the remaining characters. (Like, "ACE" is a subsequence of "ABCDE" while "AEC" is not).If the input strings are “baalllloonnn” and “balloon”, then there will be 36 different ways to select.To solve this, we will follow these steps −n := size of s, m := size ... Read More

Suppose we have one m * n matrix called mat, and an integer k, mat has its rows sorted in nondecreasing order. We can choose exactly one element from each row to form an array. We have to find the Kth smallest array sum among all possible arrays.So, if the input is like mat = [[1, 3, 11], [2, 4, 6]]1311246and k = 5, then the output will be 7, as when we choose one element from each row the first k smallest sums are [1, 2], [1, 4], [3, 2], [3, 4], [1, 6]. here the 5th sum is ... Read More

Suppose there are n people and 40 different types of hats those are labeled from 1 to 40. Now a 2D list is given called hats, where hats[i] is a list of all hats preferred by the i-th person. We have to find the number of ways that the n people wear different hats to each other. The answer may come very large, so return the answer modulo 10^9 + 7.So, if the input is like [[4, 6, 2], [4, 6]], then the output will be 4, as there are 4 different ways to choose, these are [4, 6], [6, ... Read More

Suppose we have an array called nums and an integer k, we have to find the maximum sum of a non-empty subsequence of that array such that for every two consecutive numbers in the subsequence, nums[i] and nums[j], where i < j, the condition j - i k and first element of dq is same as dp[i - k - 1], thendelete front element from dqdp[i] := maximum of dp[i] and (if dq is empty, then dp[i] + 0, otherwise first element of dp + dq[i])while (not dq is empty and last element of dq < dp[i]), do −delete ... Read More

Suppose there is a program that is used to print the array elements of an array A, but there was a little mistake in the program. In that program there was no white space after each element, so if we have one printed string, can we regenerate the array again? We know the array elements are in range 1 to k.Given the string s and the integer k. We have to find how many number of ways we can restore the array. The answer may be very large so return it modulo 10^9 + 7.So, if the input is like ... Read More

Suppose we have grid of size n x 3 and we want to paint each cell of the grid with exactly one of the three colors. The colors are Red, Yellow or Green. Now there is a constraint that is no two adjacent cells have the same color. We have n the number of rows of the grid. We have to find the number of ways we can paint this grid. The answer may be very large so return it modulo 10^9 + 7.So, if the input is like 1, then the output will be 12To solve this, we will ... Read More

Suppose Amal and Bimal are playing with piles of stones. There are several stones arranged in a row, and each stone has an associated value which is a number given in the array called stoneValue.Amal and Bimal take turns, with Amal starting first. On each player's turn, he/she can take 1, 2 or 3 stones from the first remaining stones in the row.The score of each player is the sum of values of the stones taken. Initially the score is 0. The goal of the game is to end with the highest score, and the winner is the player with ... Read More

Suppose there is a chef. And he has collected data on the satisfaction level of his n dishes. The Chef can cook any dish in 1 unit of time. Like-time coefficient of a dish is actually the time takento cook that dish including previous dishes multiplied by its satisfaction level So time[i]*satisfaction[i].We have to find the maximum sum of Like-time coefficient that the chef can obtain after dishes preparation. Dishes can be ready in any order and the chef can discard some dishes to get this maximum value.So, if the input is like [-1, -7, 0, 6, -7], then the ... Read More

Suppose we have two strings s1 and s2. The size of these strings is n, and we also have another string called evil. We have to find the number of good strings.A string is called good when its size is n, it is alphabetically greater than or equal to s1, it is alphabetically smaller than or equal to s2, and it has no evil as a substring. The answer may be very large, so return the answer modulo 10^9 + 7.So, if the input is like n = 2, s1 = "bb", s2 = "db", evil = "a", then the ... Read More

Suppose we have a string s, we have to find the longest happy prefix of s. A string is called a happy prefix if is a non-empty prefix which is also a suffix (excluding itself). If there is no such happy prefix, then simply return blank string.So, if the input is like "madam", then the output will be "m", it has 4 prefixes excluding itself. These are "m", "ma", "mad", "mada" and 4 suffixes like "m", "am", "dam", "adam". The largest prefix which is also suffix is given by "m".To solve this, we will follow these steps −Define a function ... Read More