Suppose we have a string s which represents an equation of the form x+y=z. We have to find the minimum number of digits that we need to add into s so the equation becomes true.So, if the input is like s = '2+6=7', then the output will be 2.We can turn the equation into "21+6=27" by inserting "1" and "2". So the total number of corrections required is 2.To solve this, we will follow these steps −split s into parts based on "+" character, put left part into A and right part into restsplit rest into parts based on "=" ... Read More

Suppose we are in a programming contest where there are multiple problems but the contest ends when we solve one problem. Now if we have two lists of numbers of the same length called points, and chances. To explain it, here for the ith problem, we have a chances[i] percent chance of solving it for points[i] points. We also have another value k which represents the number of problems we can attempt. The same problem cannot be attempted twice.If we devise an optimal strategy, we will have to find the expected value of the number of points we can get ... Read More

Suppose, we have N items, which are marked as 0, 1, 2, …, N-1. Then, we are given a 2D list of size S called sets. Here, we can purchase the i-th set for the price sets[i, 2], and we receive every item between sets[i, 0] to sets[i, 1]. Also, we have a list of size N called removals, where we can throw away 1 instance of the i-th element for the price removals[i]. So, we have to find out the minimum cost to purchase precisely one of every element from 0 to N-1 inclusive, or the result is -1 ... Read More

Suppose, we have a string s and another value k. We have to select some subsequences of s, so that we can get k unique subsequences. Here, the cost of selecting a subsequence equals the length of (s) - length of (subsequence). So, we have to find the lowest total cost possible after selecting k unique subsequences. If we are unable to find out this set, we will return -1. We will consider the empty string as a valid subsequence.So, if the input is like s = "pqrs", k = 4, then the output will be 3.To solve this, we ... Read More

Suppose, we have a string 'i' consisting of lowercase letters and another integer 'j'. We have to find out how many strings there are that are equal to the size of 'i' and are lexicographically smaller or equal to 'i' and having no consecutive equal characters greater than 'j'.The answer has to calculated by finding the Mod the result by 10 ^ 9 + 7.So, if the input is like i = "app", j = 2, then the output will be 405.To solve this, we will follow these steps −if j j is non-zero, thenreturn 0if pos is same ... Read More

Suppose we have two values p and q, we have to find the number of unique squares that can be generated from a grid with p rows and q columns in which the points are placed evenly. If the answer is very large return result mod 10^9 + 7. In this problem, a square is a set of 4 points that form the four vertices of a square. The sides of the square must have the same length, and it does not always have the need to be aligned with the axes of the grid.So, if the input is like ... Read More

Suppose we have a 2D list of values called 'tree' which represents an n-ary tree and another list of values called 'color'. The tree is represented as an adjacency list and its root is tree[0].The characteristics of an i-th node −tree[i] is its children and parent.color[i] is its color.We call a node N "special" if every node in the subtree whose root is at N has a unique color. So we have this tree, we have to find out the number of special nodes.So, if the input is like tree = [    [1, 2],    [0],    [0, 3], ... Read More

Suppose we have a list of words. We have to check the given words can be chained to form a circle. A word A can be placed in front of another word B in a chained circle if only the last character of A is identical to the first character of B. Every word has to be used and can be used only once (the first/last word will not be considered).So, if the input is like words = ["ant", "dog", "tamarind", "nausea", "gun"], then the output will be True.To solve this, we will follow these steps −graph := a new ... Read More

Suppose we have a 2D matrix, where the elements represent the height of a terrain. Let's imagine a situation where it will rain and all the spaces in the valleys get filled up.We have to find out the amount of rain that will be caught between the valleys.So, if the input is like666864586666then the output will be 3 as we can hold 3 units of water in between 4 and 5 squares.To solve this, we will follow these steps −Define a structure Data, that contains x and y coordinate and height hDefine a priority queue pq, it stores data items ... Read More

Suppose we have a 2D matrix named 'edges', that represents an undirected graph. Every item in the matrix 'edges' represents an edge and is of the form (u, v, w). This means nodes u and v are connected and the edge has the weight w. We also have integers a and b, that represent an edge (a, b). We have to find out if the edge (a, b) is part of a minimum spanning tree.Note − the graph has to be connected and the edge (a, b) exists in the graph.So, if the input is like edges =[[0, 2, 100], ... Read More